Pea Puffer Care Sheet
- Macauley Sykes
- Oct 31, 2020
- 26 min read
Updated: 14 hours ago
This care sheet has been created to guide aquarists toward providing truly optimal care for this species. Not just the minimum needed for survival, but the conditions in which they can genuinely thrive.
At Pufferfish Enthusiasts Worldwide, we are dedicated to promoting the highest standards of husbandry by blending scientific research, field observations, and hands-on experience. Our goal is to empower fishkeepers everywhere to support the long-term health, natural behaviour, and conservation of pufferfish.
Every PEW guide begins with a simple principle: to follow nature’s lead. We start by asking how a species lives in the wild, how it hunts, rests, interacts, and adapts to the rhythm of its environment. Only then do we begin shaping the guidance for captivity.
Every recommendation we make, from water chemistry and lighting to aquascaping, tank size, and diet, grows from this foundation.
By understanding the wild origins of these fish, we learn not just how to keep them alive, but how to help them express their true nature. That is what responsible fishkeeping means to us, and it is the spirit in which this guide was written.
Introduction
The Pea Puffer (Carinotetraodon travancoricus) is a truly fascinating species of freshwater pufferfish, endemic to the lush and biodiverse region of Kerala (historically known as Travancore) in southwestern India. This intricate landscape of rivers, lakes, and wetlands provides the perfect natural habitat for a fish that has captured the hearts of aquarists worldwide.
At only about 25 millimetres long - barely an inch - the pea puffer holds the title of the world’s smallest pufferfish. Despite their size, they make up for it with sharp awareness and bundles of personality. Over the years, aquarists have given them a few affectionate nicknames: pea puffers, pygmy puffers, and dwarf puffers. In this guide, we’ll stick with the one most people know best: the pea puffer.
They’re now one of the most common pufferfish in home aquariums, yet confusion about how to care for them still runs deep. Too many guides miss the mark, overlooking how social these little fish really are, or suggesting diets and tanks that don’t come close to what they need. Sadly, that means many pea puffers never get the chance to live as fully as they could.
Taxonomic History and Identification
Carinotetraodon travancoricus was originally described in 1941 as Tetraodon travancoricus by Hora & Nair. Later taxonomic revisions placed it in the genus Carinotetraodon to better reflect morphological distinctions from the broader and more heterogeneous Tetraodon group.
These revisions were based on differences in body form, dentition, and osteology, which indicated that dwarf species from South and Southeast Asia formed a more natural grouping separate from the mainly African Tetraodon species.
It’s also worth noting that C. travancoricus is sometimes confused with a very similar species, Carinotetraodon imitator, described much later in 1999. The two look nearly identical, but C. imitator tends to be rarer in the trade and has subtle differences in colour pattern and distribution. For aquarists, both species require the same care, but correct identification remains important for conservation and breeding efforts.
In The Wild
Pea puffers (Carinotetraodon travancoricus) are endemic to India’s Western Ghats, confirmed from Kerala and into southern Karnataka. The type locality is the Pamba (Pampa) River in central Travancore. Records include at least 13 Kerala river systems, such as the Pamba, Periyar, Chalakudy, Bharathapuzha, and Kabini, as well as connected lowland wetlands/backwaters such as Vembanad and the Thrissur “kole” wetlands. They are also documented from the Kallar stream within Neyyar Wildlife Sanctuary (southern Kerala).
In the wild, pea puffers favour sluggish, heavily vegetated waters with overhanging banks, leaf litter, and complex edge cover. Substrates at verified sites range from gravel/rock to clay-loam with silt and sand. Measured field conditions at Kallar were 25–28 °C with a pH of 7.3–8.0.
They not only occur in natural streams and oxbows but also in man-made waters linked to those systems (ditches, irrigation channels, inundated paddy pits, and abandoned tanks), especially in the lowlands.
The rivers of the Western Ghats are ruled by the rhythm of the monsoon. In the Chalakudy basin of Kerala, rain sweeps in from June to September, followed by a calmer post-monsoon stretch through October to January, and then the dry pre-monsoon months leading into summer. When the rains come, the rivers swell and spill into the floodplains, the water softens, and the temperature drops. Once the dry season returns, the flow slows, levels fall, and the water grows harder and more mineral-rich. Territories tighten as pools shrink and clarity returns.
These natural cycles seem to shape almost everything the local puffers do. Feeding, breeding, and even how they move through their habitats all follow the changing pulse of the river. Observations made throughout the year make this pattern unmistakable.
Peer-reviewed gut analyses show a bottom-oriented, animal-heavy diet: adults skew toward aquatic insects (Odonata, Ephemeroptera, Diptera) and small crustaceans (cladocerans, copepods, ostracods). Algae/diatoms are also present, with seasonal shifts tied to flow and productivity. Across a full year in the Chalakudy River, adults preferred insects (~28–32%) and crustaceans (~23–30%), with annelids and algal matter varying by season. Another Kerala study (Kallar/Neyyar) classified them as carnivorous with frequent sand/detritus in stomachs, consistent with benthic picking.
Pea puffers don’t live alone. In the wild, they’re usually seen in small, loose groups, slipping in and out of tangles of plants, tree roots, and leaf litter along the river margins. This “safety in numbers” helps them avoid predators and gives them plenty of opportunities to forage together.
Co-occurring Fishes
These puffers are far from the only residents of these waters, which is one of the richest freshwater fish regions in the world.
Assemblages vary by river and reach, but verified checklists from the same basins/streams where pea puffers occur include:
Topminnows & danionins: Aplocheilus lineatus (striped panchax), Devario malabaricus, Rasbora dandia (now often placed in Devario).
Barbs & allies: Dawkinsia filamentosa (filament barb), Haludaria fasciata, Pethia punctata, Puntius mahecola.
Garra & loaches: Garra mullya, Mesonoemacheilus triangularis.
Cichlids (Kerala chromides): Etroplus suratensis (green chromide) and Pseudetroplus (Etroplus) maculatus (orange chromide) in backwater-connected fresh to oligohaline reaches.
Snakeheads & catfishes: Channa diplogramma, Channa gachua, Mystus spp. (Compiled from Vamanapuram/Kallar, Chalakudy, and Periyar basin records.)
Conservation Status & Pressures.
Pea puffers may be tiny, but they come from a part of the world under real pressure. The Western Ghats are one of India’s biodiversity hotspots, yet the rivers and wetlands here have been changing fast. Dams and water diversion projects alter the natural flow of streams, deforestation leads to siltation and loss of shady margins, and pollution from agriculture and industry seeps into lowland wetlands. On top of that, paddy fields and backwaters where puffers once thrived are often drained, filled, or converted.
Because of these threats, the pea puffer is officially listed as Vulnerable on the IUCN Red List. Surveys in parts of Kerala have shown worrying population drops. In some places, populations have declined by 30–40% over just a decade.
Habitat change alone would be a big enough challenge, but there’s another pressure too: the aquarium trade. For many years, the vast majority of pea puffers sold worldwide were wild-caught, and export numbers have been very high compared with other small endemic fish from the region.
The good news is that this is starting to change. Breeding programs in Europe and Asia are now producing more tank-bred puffers, which means aquarists have the option to choose fish that aren’t taken from dwindling wild populations.
In the Aquarium
Few fish win people over quite like the Pea Puffer. Barely 2.5 centimetres long when fully grown, these tiny hunters have become the world’s most popular pufferfish. Their small size makes them easy to house, but it’s their intelligence and bold little personalities that make them unforgettable. Once collected almost entirely from the wild, they’re now bred by both commercial farms and dedicated aquarists. It is a very positive step for a species whose native waters are increasingly under threat.
Pea Puffers do best in aquariums that feel alive. Dense planting, twisting wood, and rockwork give them cover and help them feel safe. In nature, they are cautious by instinct, small fish in big spaces, wary of anything unfamiliar. When their tank feels enclosed and secure, that anxiety fades. They begin to glide confidently through every corner, pausing to watch, explore, and interact in ways that make them endlessly fascinating to observe.
Almost any aquascape can work if it offers enough structure. Driftwood such as red moor or mopani, smooth stones, and pieces of lava rock or dragon stone all make great foundations. Plants like Java fern and Anubias can be attached to hardscape to add height and texture, while background stems such as Limnophila sessiliflora or large Amazon swords create a canopy that filters the light and softens reflections. Moss is especially valuable. Java (Taxiphyllum barbieri), weeping (Vesicularia ferriei), and Christmas moss (Vesicularia montagnei) form soft cushions that puffers love to rest on. When they spawn, those same mats protect their eggs and fry.
In their natural habitat, Pea Puffers are often found in shallow, slow-moving waters shaded by floating plants such as duckweed. Replicating this environment with Amazon frogbit, water lettuce, or similar species adds a sense of safety and natural shade. Floating plants diffuse the light, soften
reflections, and recreate the dappled surface cover that protects wild puffers from predators like kingfishers, herons, and cormorants.
When aquariums are designed with these natural cues in mind, puffers become more active, expressive, and engaging to watch. The beauty of this approach is that what benefits the fish also enhances the aquascape itself, creating a living, layered underwater garden where your fish can truly thrive and you can take pride in the world you have built for them.
Water movement should be gentle to moderate. Pea Puffers are not strong swimmers, so powerful currents can tire them quickly and should be avoided. More important than flow is water quality, as this species is highly intolerant of poor conditions. Regular maintenance and large, consistent water changes are key. A good rule of thumb is to replace around half the water each week to maintain stability and prevent waste from building up.
Under proper care, Pea Puffers can live far longer than many aquarists expect. While most sources suggest an average lifespan of three years, healthy, well-maintained individuals often reach six years or more. Longevity is strongly influenced by temperature, diet, and water quality, with cooler, cleaner systems generally supporting a longer life.
Substrate
Pea Puffers, like many members of the genus Carinotetraodon, sometimes display a surprising behaviour.
When startled, they may dive straight into the substrate to hide, disappearing in an instant. Not every individual does this, but for those that do, it is an instinctive escape response that helps them feel secure.
In their native rivers, these fish are often found over sandy or silty beds scattered with leaf litter, where they forage among the detritus for small invertebrates. This mix of soft sediment and organic cover offers both food and shelter. To reflect this in the aquarium and to prevent injury, a fine, smooth sand substrate is always the safest choice. Coarse gravel or sharp materials can cause harm if a puffer attempts to bury itself.
If you wish to use nutrient-rich plant substrates or aquasoils, cap them with a layer of fine sand at least 1.5 centimetres deep. This creates a natural, protective surface that encourages natural behaviour while keeping your aquascape stable and visually cohesive.
Group Size and Social Behaviour
Spend a little time watching Pea Puffers in their natural setting and the difference is obvious. They don’t keep to themselves like other puffers. Instead, they form loose groups, drifting through the weeds together, stopping now and then to pick at tiny prey. It feels social, even coordinated in a quiet way. Living close to others gives them a sense of safety. When one fish spots movement, they all seem to know.
To really understand Pea Puffers, it helps to picture them where they belong, in the wild. In one rare piece of footage, a broad shoal moves slowly through a few inches of water, weaving between stems and fallen leaves with easy coordination. You can almost see them reading one another’s movements. Each flick of a fin, each small change of direction, shows how social they are by nature.
Watching them like this makes it clear why we should aim to capture that same sense of community in our aquariums. It is how they are meant to live.
Life in a group gives Pea Puffers a kind of calm confidence. They feed together, explore together, and seem far more relaxed when surrounded by their own kind. That instinct does not fade in captivity. In tanks that offer space, shelter, and company, they are alert, curious, and full of character. Left on their own, things change. A solitary puffer often becomes withdrawn or edgy, sometimes even aggressive. These are signs of a fish that has lost the social contact it depends on.
Research into other shoaling species supports what experienced keepers observe with Pea Puffers. Studies on tetras, danios, and barbs have shown that individuals kept in groups have lower stress hormone levels, slower metabolic rates, stronger immune responses, and higher growth rates than those kept alone. Group living provides psychological stability, reduces vigilance fatigue, and allows energy to be spent on growth and healing rather than constant alertness.
These same biological advantages explain why Pea Puffers in groups are healthier and more resilient than solitary ones.
Within any properly sized group of Pea Puffers, a social hierarchy naturally forms. Dominant and subordinate individuals each find their place, and this structure helps maintain stability within the group. Scientific research supports this pattern across many fish species. A meta-analysis examining stress hormone levels in social fishes found that differences between dominant and subordinate individuals were far greater in small groups, such as pairs, than in larger ones. In other words, the smaller the group, the more intense and concentrated the stress becomes for lower-ranking fish. Larger groups dilute that pressure, allowing subordinates to avoid constant confrontation and recover more easily from displays of dominance.
This finding mirrors what we see in aquariums. In small groups of Pea Puffers, one or two individuals often receive repeated aggression from dominant fish. In groups of six or more, that tension is shared across the hierarchy, and no single fish bears the full brunt of social stress. This is one of the clearest biological reasons why larger groups are not only more peaceful but also healthier overall.
Over years of keeping and observing these fish, and through conversations with thousands of aquarists around the world, one conclusion stands out. Groups thrive. Singles do not. In tanks where at least six Pea Puffers are kept together, aggression is distributed, hierarchy is more balanced, and individuals live longer, healthier lives. Smaller groups, by contrast, often experience stress and infighting because there are too few fish for natural social structure to form.
Dominance behaviour is normal and even healthy, but when there are only two or three fish, one may receive the full brunt of that aggression. With larger numbers, tension spreads out, and no single individual is singled out. This mirrors what happens in the wild, where puffers use numbers and structure to maintain stability within their group.
Behaviour also changes as the fish mature. Juveniles are often tolerant and exploratory, while adults establish territories and social ranks. A larger group allows for this natural transition without forcing constant conflict. Small groups might appear peaceful at first, but that balance rarely lasts.
Through our own experience at Pufferfish Enthusiasts Worldwide and the shared knowledge of our global community, we are confident that keeping Pea Puffers in groups of six or more is the only reliable way to ensure long-term success in captivity. These fish are social by nature, and that social need is not optional.
When Pea Puffers are kept alone for too long, they begin to express stress behaviours, including restlessness, fixation, and heightened aggression. Some may become so conditioned to solitude that reintegration later becomes impossible. This should not be seen as an argument for keeping them singly, but as a reminder that their well-being depends on companionship. Keeping them in groups allows them to live as nature intended. They remain alert, expressive, and at ease within the community of their own kind.
The Differences Between Shoaling and Schooling
There are two main types of fish groupings: schools and shoals.
A school is a tightly coordinated group that moves as one, with each fish mirroring the movements of its neighbours. Schooling species form these patterns instinctively, turning and gliding together almost like a single organism.
Pea Puffers do not behave this way. They are shoaling fish, not schooling fish.
A shoal is a looser, less synchronised gathering in which individuals swim independently but stay close enough to remain connected. They move together socially rather than mechanically.
Shoaling offers safety in numbers. When a potential threat is nearby, the group instinctively closes ranks, but once the danger passes, each fish resumes its own course. It is easy to mistake this for schooling, yet the distinction is important. Recognising that Pea Puffers shoal rather than school helps us understand their true nature and design our aquariums to meet their social needs.
Male-to-Female Ratio
Male Pea Puffers are naturally more territorial and competitive than females. In mixed groups, this means that males are more likely to spar and claim small patches of territory, especially as they mature. To keep harmony within the group, it is best to limit the number of males wherever possible.
There is no fixed formula, but a good guideline is to keep at least two females for every male. This ratio helps maintain balance, reduces the frequency of disputes, and gives females a break from constant attention.
For example, in a group of six puffers, four females and two males usually create a stable and peaceful social structure. Larger groups make this balance easier to maintain, since aggression is distributed more evenly and individual differences have less impact on group dynamics.
Tank size
For a healthy and stable group, six Pea Puffers should be housed in no less than 60 litres (15.8 US gallons). This size offers enough territory for natural behaviour and allows the group to establish a balanced social structure. In regions where 60-litre aquariums are uncommon, such as the United States, a 20-gallon long (≈76 litres) makes an excellent starting point. Of course, providing a larger tank is always beneficial.
As a general guideline, allow around one Pea Puffer per 10 litres (≈2.6 US gallons) of water. This ratio has proven effective through years of observation, balancing social space with water quality and filtration capacity. It provides enough room for each fish to establish its own patch without isolating them from the group.
Larger tanks not only reduce aggression but also make it easier to maintain clean, stable water. They offer more scope for planting, scaping, and creating the visual barriers that help puffers feel secure. In essence, more space gives you more control and gives the fish a more natural, comfortable environment to explore.
Examples of long-term stocking:
60 L (15.8 US gal) → 6 pea puffers (minimum group size)
80 L (21 US gal) → 8 pea puffers
100 L (26 US gal) → 10 pea puffers
120 L (32 US gal) → 12 pea puffers
150 L (40 US gal) → 15 pea puffers
These numbers are guides, not strict limits. Larger tanks with thoughtful planting and layout can often support slightly higher numbers, while smaller setups run into problems quickly. Always design with the fish’s welfare first, and let space and structure work in your favour.
The "5 and then 3 gallon" Recommendation
Many aquarists have heard the old guideline that suggests 5 US gallons, or about 19 litres, for the first Pea Puffer and another 3 gallons for each one after that. It appears everywhere online, yet there is no real research or long-term evidence behind it.
In practice, this rule gives the wrong impression. It underestimates how much room these busy little fish need, and it assumes they should live alone. Pea Puffers are naturally social, forming loose groups in the wild. When they are kept in tanks that follow the old “5 and 3” formula, problems appear quickly. The setups tend to feel cramped, which leads to tension, unstable water quality, and stressed fish.
At Pufferfish Enthusiasts Worldwide, we recommend a very different approach: one Pea Puffer for every 10 litres, or roughly 2.6 US gallons, and never fewer than six fish together. This guideline comes from both observation and years of experience among dedicated keepers. It allows natural behaviour, steady water conditions, and far healthier, more confident fish.
In short, that old stocking rule survives mostly through repetition. When we give these fish the space and company they truly need, the difference in their behaviour and well-being is remarkable.
Water Values
Maintaining the right water values is one of the most important parts of pea puffer care. While they are adaptable compared to some freshwater species, their long-term health and behaviour are strongly tied to clean, stable conditions that echo the rivers of Kerala and southern Karnataka, where they evolved.
Maintain the following water values for long-term success with pea puffers:
pH: 6.8–7.8 (stable around 7.2–7.5 is ideal)
Temperature: 25–28 °C (75–82 °F)
Nitrate (NO₃): <15 ppm (aim for as close to zero as you can manage)
GH: 7–12 dGH (≈120–200 ppm) is ideal; tolerances from 5–25 dGH have been reported
KH: 4–7 dKH, enough to buffer against pH swings
TDS: 180–250 ppm when GH/KH are in range
Why these numbers?
Field surveys from the Pamba, Chalakudy, and Bharathapuzha river systems consistently record pH values between 7.2 and 8.0, temperatures around 25–28 °C, and moderate hardness (typically 100–200 ppm CaCO₃). Conductivity readings from these habitats often fall between 200 and 300 µS/cm, reflecting a balance of dissolved minerals from lateritic soils and limestone bedrock. These conditions are neither soft and acidic nor fully alkaline, but hover around neutral with enough buffering to remain stable even in warm, shallow environments.
The ranges we recommend for captive care mirror this equilibrium. They provide enough mineral content to stabilise pH without exceeding the tolerance of delicate plants or microorganisms that thrive alongside Pea Puffers. A stable midpoint, around pH 7.2–7.5, offers the best compromise between natural chemistry and practical aquarium maintenance.
While Pea Puffers tolerate brief fluctuations, they show their best colour and most consistent activity at 25–28 °C (75–82 °F), which aligns closely with field temperatures in their native range. Cooler conditions slow their metabolism and can suppress appetite, while hotter water accelerates ageing and reduces dissolved oxygen. A steady middle ground around 26 °C supports both comfort and longevity.
In the wild, nitrates are virtually absent thanks to constant water turnover, dense vegetation, and microbial processing. Captive systems cannot replicate that flow, so maintaining nitrate under 15 ppm (ideally below 10 ppm) is the next best thing.
This is not a toxicity threshold but a quality target. In our experience, Pea Puffers kept in exceptionally clean water display richer colouration, more social confidence, and fewer health problems than those exposed to higher nitrate concentrations.
Tankmates
Pea puffers are almost as well known for nipping fins as they are for their tiny size. For this reason, the safest and most reliable option is a species-only aquarium.
That said, behaviour changes when they are kept in large shoals (20+ individuals) within spacious aquaria. In these setups, puffers are so engaged with one another that they often pay less attention to any other fish.
Even then, any tankmate is added at the keeper’s risk, and close monitoring is essential. If harassment or fin-nipping occurs, be prepared to separate fish immediately.
Suitable companions must be:
Peaceful and non-aggressive
Fast-swimming and alert enough to avoid attention
Short-finned, with no trailing fins to tempt bites
Comfortable in the same water parameters
Not in direct competition for food or space
This rules out popular choices like guppies, angelfish, gourami, bettas, and barbs.
Ideally, companions should also come from similar biotopes to the pea puffer.
Some aquarists experiment with small, tight-schooling fish that meet these criteria. Options such as chilli rasboras (Boraras brigittae), mosquito rasboras (Boraras urophthalmoides), or celestial pearl danios (Danio margaritatus) can sometimes coexist in large, plant-dense tanks where the puffers are kept in substantial numbers. Even then, success is never guaranteed, though: companions may spend much of their time hiding, lose their natural shoaling behaviour, or gradually dwindle under puffer attention.
Most importantly, the aquarium must be designed to accommodate the welfare of all species present. That means providing adequate swimming space, cover, and enrichment not just for the puffers, but also for any schooling fish or bottom-dwellers. A tank that is only “safe enough” for the puffers but leaves their companions stressed or hiding is not a successful community.
For most aquarists, pea puffers are still best enjoyed in their own dedicated aquarium. But for those determined to try a layered community, choose companions carefully, build the tank around dense planting and broken sightlines, and always keep a backup plan in case things don’t work out.
What About Shrimp?
Small shrimp are often suggested as tankmates, but while some keepers report a harmonious relationship between their Pea Puffers and small shrimp such as the Red Cherry (Neocaridina davidi) or Amano (Caridina multidentata), others report carnage. The results with shrimp vary
Predator–prey instinct. Shrimp are the perfect size and shape to trigger hunting behaviour. They may be chased, nipped, and stressed until they disappear.
Lack of defence. Shrimp have delicate appendages and soft exoskeletons that make them easy targets for curious puffers.
Behavioural overlap. Shrimp forage across leaves, wood, and moss (the very same microhabitats puffers patrol), so direct encounters are inevitable.
Baby shrimp stand almost no chance. In mixed tanks, any shrimplets that appear are usually hunted down within hours. Only the largest and best-hidden adults are likely to persist, and even then, they may never feel truly secure.
Some aquarists with very large, mature, and plant-dense tanks do manage to maintain small shrimp colonies, but this is typically due to the shrimp's fast breeding and heavy cover. For most keepers, shrimp will eventually become an expensive live food source rather than a permanent addition.
If you want to try shrimp, use them in densely planted tanks with abundant moss, leaf litter, and hardscape crevices to give them every possible hiding place. Accept from the start that you may lose individuals, and that babies will almost certainly not survive.
Otocinclus catfish
Otocinclus are sometimes considered as potential companions because they are peaceful, algae-grazing catfish that generally ignore other fish. In the right circumstances, they can coexist with pea puffers, but only under particular conditions. Otocinclus are also a shoaling species, being found within shoals of thousands in the wild, and because they are obligate aufwuchs eaters, the tank needs to be both large enough and mature enough to support a group. Keeping them properly requires as much thought and preparation as the puffers themselves.
Sexual Dimorphism
Juvenile pea puffers (Carinotetraodon travancoricus) are very difficult to sex, but clear differences emerge as they mature.
Males: develop a dark ventral stripe running lengthwise along the underside, and show fine iridescent “wrinkles” or lines around the eyes. Their bellies often take on a yellow to golden sheen, and flank spots may merge into short lines or ovals. During courtship, males can also display small dorsal and ventral crests.
Females: are generally rounder-bodied, especially when carrying eggs, and lack both the continuous belly stripe and the eye “wrinkles.” Their spots tend to remain distinct.
These traits are not so obvious in young fish; accurate sexing usually only becomes possible once the puffers are near full size.
Buying Your Pea Puffers
Whenever possible, visit the store in person to hand-select the individuals for your shoal rather than buying unseen online. This allows you to assess their condition and choose strong, healthy fish.
Unfortunately, pea puffers are sometimes offered in a malnourished state, and it can be difficult (especially for new keepers) to nurse them back to full health.
Look for puffers that are bright-eyed, alert, and active, with plump, rounded bodies and no signs of hollow bellies or illness. Healthy fish should show curiosity about their surroundings and respond quickly to movement. Avoid any individuals who look thin, lethargic, or uninterested in food.
It’s also worth asking about the source of the fish. Pea puffers are classified as Vulnerable on the IUCN Red List due to habitat loss, pollution, and collection pressure. The aquarium trade is not the only threat, but we can help by supporting responsible practices. If possible, choose captive-bred specimens and don’t hesitate to ask your retailer where their stock has come from. Each purchase is an opportunity to support the future of this remarkable species.
Quick Buying Checklist:
Active and alert, responds to movement
Bright, clear eyes
Plump, rounded body (no hollow belly)
Shows interest in food
No visible injuries, sores, or clamped fins
Introducing New Members to an Existing Shoal
The easiest and most harmonious way to establish a group of pea puffers is to buy all the individuals for your shoal from the same place, at the same time. This ensures that they all settle into the aquarium together, with no one fish having an established territorial advantage.
If you need to add new puffers to an existing group, take a few precautions to minimise conflict:
Match sizes: Choose new puffers that are roughly the same size as the established members. Very small newcomers may be bullied, while much larger individuals can dominate.
Rescape before adding: Rearranging plants, wood, and rocks before introducing the new fish helps to break up established territories and “resets” the social structure.
Observe closely: Monitor the group carefully in the first days after introduction. Some chasing and posturing are normal, but persistent targeting of one individual is a sign that separation may be needed.
With patience and planning, most groups will settle into a new balance within a short time.
Treating for Parasites
Wild-caught Pea Puffers often arrive with internal or external parasites, most commonly nematodes and protozoans. Where possible, confirm infection through observation or microscopic examination before administering treatment.
For new arrivals, a 4-6 week quarantine period allows safe monitoring and targeted medication if symptoms appear.
Levamisole HCL (e.g. eSHa NDX) is our recommended first-line medication. It is highly effective against nematodes (roundworms), including Capillaria, Eustronggylides, Camallanus, and Contracaecum, as well as stomach worms, nodular worms, hookworms, and lungworms.
Praziquantel (e.g. PraziPro) should be used when cestodes (tapeworms) are suspected, as Levamisole is not effective against them.
Be aware that small crustaceans can serve as intermediate hosts for certain parasites. Depending on what you feed and where it is sourced, you may need to worm your fish periodically.
Antibiotic-based medications
Antibiotic-based medications should never be used for worming fish unless prescribed by a qualified veterinary professional. This includes drugs with active ingredients such as Metronidazole, Kanamycin, and Erythromycin. In many countries, the use of antibiotics without veterinary oversight is also illegal.
There are several reasons for this caution:
Gut microbiota damage. Antibiotics do not discriminate between “good” and “bad” bacteria. They can disrupt the delicate microbial community that lives in the digestive tract and plays a vital role in digestion, nutrient absorption, immunity, and disease resistance. When beneficial bacteria are reduced, pathogenic bacteria often fill the gap, leaving the fish more vulnerable to illness. One of the clearest signs of disturbed gut flora is a loss of appetite due to digestive discomfort, especially dangerous in newly imported fish that need to regain strength.
Impact on the aquarium ecosystem. Antibiotics can also wipe out the beneficial microorganisms that maintain the nitrogen cycle. This can destabilise the aquarium, leading to dangerous spikes in ammonia and nitrite.
Antibiotic resistance. Perhaps most seriously, indiscriminate use contributes to the rise of resistant bacterial strains. Once established, these infections are far harder (sometimes impossible) to treat. Resistant strains of Aeromonas, Pseudomonas, and Flavobacterium columnare (Columnaris) have all been reported in aquaria following inappropriate antibiotic use.
Antibiotics are powerful tools when used correctly, but misusing them can do far more harm than good, for both your fish and the wider aquarium community. For worming, always stick to dedicated antiparasitic treatments such as Levamisole HCL or Praziquantel, and leave antibiotics for situations where they are prescribed by a veterinary professional.
Notable behaviour
Pea puffers have big personalities packed into tiny bodies, and their behaviour is one of the reasons they are so beloved.
A few traits are worth highlighting:
Jumping: When startled or chased by another puffer, they may leap clear out of the water. For this reason, they must always be housed in an aquarium with a tight-fitting lid to prevent accidents.
Begging for food: Highly intelligent and quick to learn, pea puffers often recognise their keeper and will eagerly beg at the glass when they associate you with feeding time. This interaction is one of their most endearing qualities.
Circling with curved tails: Puffers may occasionally circle one another with their tails curved. This is usually a defensive display or part of a brief territorial spat, and it is perfectly normal as long as it remains short-lived. The same behaviour may also appear when a fish is cautiously inspecting an unfamiliar object in the tank.
Feeding
At Pufferfish Enthusiasts Worldwide, we always encourage keepers to replicate the natural diet of their pufferfish as closely as possible. In the wild, pea puffers feed on a diverse range of tiny aquatic invertebrates, and it is your responsibility as a keeper to provide the same variety in captivity.
A varied diet is not just about flavour and enrichment.
Offering different foods ensures a broad spectrum of nutrients that support healthy growth, development, and long lifespans. Variety also stimulates natural hunting behaviours, keeping your puffers engaged and active.
Pea puffers rarely accept flake or pellet food, and they generally ignore freeze-dried options. For this reason, a diet based on live and frozen foods is essential. They usually attack these with great enthusiasm.
Our preferred foods for these fish include:
Pinhead crickets
Aphids
Glassworm (phantom midge larvae)
Grindal worm
Daphnia/water flea (live or frozen)
Small snails - read below
Small earthworm (wisps)
Blackworm
Whiteworm
Copepod
Food suitable in moderation:
Bloodworms: Wildly popular with puffers, but should be limited due to nutritional imbalance, digestion issues, and contamination risk. Natural analogue = chironomid larvae, but over-reliance in captivity is a problem.
Artemia (adult brine shrimp): Useful but not very rich in long-chain fatty acids unless gut-loaded; fine as part of variety.
Important feeding guidelines:
Do not feed krill, cockle, mussel, clams, oysters, or other similar molluscs. They are marine molluscs rather than small freshwater snails; pea puffers don’t have the jaw strength or ecological adaptation to consume these.
No single food should make up more than 20% of the diet.
Bloodworms should not exceed 10% of the diet (see note below).
Alternate between different foods daily, and feed several small meals rather than one large one. This not only balances nutrition but also provides constant enrichment, as the puffers spend much of their day hunting and exploring.
Why limit bloodworms?
Bloodworms (larvae of non-biting midges, family Chironomidae) are cheap, widely available, and eagerly accepted by pea puffers. In fact, they are often their favourite food. But this is exactly why caution is needed: we all too often see pea puffers consume far too many bloodworms, simply because they are taken so readily.
For the fish:
Poor nutritional balance: High in protein but lacking essential fatty acids, vitamins, and minerals. Over-reliance can cause long-term deficiencies.
Digestive issues: Their chitinous casings can be hard to process in large amounts, sometimes leading to bloating or constipation.
Contamination risk: Live or frozen bloodworms may carry pathogens or pollutants from their collection sites.
For the keeper:
Allergic reactions: Bloodworms are a well-documented cause of contact and respiratory allergies in aquarists. Symptoms range from rashes and itching to asthma-like attacks or, rarely, anaphylaxis.
Dust sensitisation: Freeze-dried bloodworms can release fine particles that trigger respiratory issues with repeated exposure.
Cross-reactivity: Individuals allergic to shrimp, crabs, or insects may be more prone to reacting.
Hygiene: As with any live or frozen food, poor handling can spread bacteria or parasites, though this is less common.
Safety tips:
Handle with tweezers or gloves, not bare hands.
Wash thoroughly after use.
Avoid freeze-dried forms if you have a history of allergies or asthma.
Bloodworms are best treated as an occasional food, not a staple. Use them to add variety, but balance with other options such as snails, worms, and small crustaceans that more closely replicate the pea puffer’s natural diet.
Feeding snails and hard-shelled foods
Pea puffers will readily eat small freshwater snails such as ramshorn snails (Segmentina nitida) and bladder snails (Physella acuta). Offering snails is a good way to mimic part of their natural diet and provide enrichment, but it is not something that needs to be done every day.
Unlike many larger puffer species, pea puffers do not have beaks that grow rapidly, so they do not require frequent hard-shelled foods to keep their teeth worn down. Occasional small snails are sufficient to meet their needs.
It is best to avoid larger snails. Pea puffers will often attack them by repeatedly nipping at the exposed foot, injuring or killing the snail without consuming it. The result is a rotting body that can quickly foul the water. Because snails are protein-rich, even a single uneaten carcass can release a surge of ammonia into the water, especially in smaller tanks.
For this reason, stick to small, soft-bodied snails that can be consumed completely, and always remove any uneaten remains promptly.
Filtration and tank maintenance
Pea puffers are highly sensitive to poor water conditions, so their aquarium must be equipped with strong biological and mechanical filtration to handle the waste they produce. Clean, stable water is one of the cornerstones of long-term success with this species.
Good filtration alone is not enough. Consistent husbandry is just as important:
Carry out regular water changes to keep nitrate (NO₃) levels below 15 ppm, and ideally as close to zero as possible.
As a baseline, we recommend a minimum 50% water change every seven days. Many keepers find that more frequent or larger changes yield even better results, especially in heavily stocked or smaller tanks.
Pay close attention to the base of the scape, where detritus can accumulate in dense planting and hardscape. Siphon gently around these areas to prevent hidden waste from degrading water quality.
Why keep nitrates low?
While nitrates are far less immediately toxic than ammonia or nitrite, chronic exposure to elevated nitrate has measurable negative effects on fish health.
Studies across freshwater species have shown that long-term nitrate stress can:
Suppress immune responses, making fish more prone to bacterial and parasitic infections
Reduce growth rates and feed efficiency, particularly in juvenile and active species
Impair reproduction and shorten lifespan when levels are allowed to remain consistently high
For sensitive, active species like pea puffers, nitrate is not just a number; it’s a slow-acting stressor. Keeping it as close to zero as possible will support stronger immunity, brighter colours, and longer, healthier lives.
Inflation
Pea Puffers can inflate themselves when frightened or stressed.
They should never be provoked into inflating!
If the fish needs to be moved for whatever reason, it should be herded into a watertight container under the surface of the water to prevent it from inhaling air.
Toxicity & toxin origin
There is no verified evidence that Carinotetraodon travancoricus contains tetrodotoxin or saxitoxins. Broad reviews of pufferfish toxins do not list this species among confirmed toxic taxa, and no peer-reviewed biochemical detections have been published to date. Keepers should therefore treat Pea Puffers as non-toxic in the practical aquarium sense, while acknowledging that future studies could always refine this picture.
Where toxins do occur in pufferfish, they are typically acquired ecologically rather than synthesised de novo. Marine and euryhaline species often accumulate tetrodotoxin through diet and associated microbiota, a pathway demonstrated across multiple genera. Freshwater Southeast Asian Pao species, by contrast, have repeatedly shown saxitoxins, and toxicity disappears in captivity without environmental sources, which supports a dietary origin. These patterns are genus, habitat, and food-web specific.
By way of context, TTX has been confirmed in the brackish water puffer Tetraodon nigroviridis, while Cambodian freshwater Pao spp. carry saxitoxins. These cases are ecologically and taxonomically distinct from Carinotetraodon. Extrapolating toxin status across genera is therefore unreliable.
Keeper guidance. There is no evidence-based rationale to handle Pea Puffers as toxic animals in the home aquarium. Standard aquarium hygiene is sufficient. Avoid sensational claims of “TTX puffers” for this species unless and until peer-reviewed analyses demonstrate otherwise. If new data emerge, this section will be updated with precise methods and tissue-specific results.
Disclaimer
Pufferfish health information given on this site is not intended to act as or replace the advice of a certified veterinary professional. If your pufferfish is experiencing a medical emergency, contact an experienced aquatic veterinarian immediately.
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The main priority at Pufferfish Enthusiasts Worldwide will always be to provide the most accurate and up-to-date information pertaining to individual species and their care. Although we do greatly encourage the use of binomial names (scientific names) because common names can be so misleading for pufferfish, we sometimes have to make concessions for SEO reasons.
We realise that most people are not going to search "Carinotetraodon travancoricus care" and are instead more likely to search for "pea puffer care", so this care sheet refers to them by their most frequently used common name, so that new and prospective owners will be able to find this information through a Google search.
