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Pao Baileyi Pufferfish Care Sheet

Updated: Oct 25, 2020

This care sheet is written with the aim of providing the optimal care for this species of fish.

Pufferfish Enthusiasts Worldwide endeavours to inspire and promote the highest standards of care - not basic or minimum care - using the best evidence available at the time

Photo credit: Ryan Bullock
Pao baileyi

The baileyi is a species of freshwater pufferfish belonging to the Pao genus.

The P.baileyi previously belonged to the Monotrete and then the Tetraodon genera, until being reassigned in 2013 to Pao.

The species was discovered in 1985 and the specific name honours Professor Dr. Reeve M. Bailey, Professor of Biological Sciences and Curator of Fishes in the Museum of Zoology.

The cirri (epidermal outgrowths) that resemble hairs on the P.baileyi have earned it the common name of Hairy Puffer.


In the wild

The P.baileyi populations in the wild are still healthy in suitable habitats and it is considered 'Least Concern' by the International Union for Conservation of Nature (IUCN).
Mekong River, Thailand-Laos Border

P.baileyi is only found in the Mekong basin in Thailand and Laos.

It has been observed to nestle itself tightly within the crevices of the rock found in the fast flowing, highly oxygenated waters of the Mekong mainstream and its larger tributaries.

The P.baileyi populations in the wild are still healthy in suitable habitats and it is considered 'Least Concern' by the International Union for Conservation of Nature (IUCN).

The P.baileyi disguises itself as a rock, sitting motionless with only the cirri flowing with the current, imitating algae. It remains there, or wallowed in the substrate, ready to launch a surprise attack on any prey items that come within striking distance. It feeds on smaller species of fish, freshwater crustaceans and benthic animals such as worms.


In the aquarium

The P.baileyi is a popular choice for ‘oddball’ enthusiasts and imports of wild-caught specimens are quite common.

This pufferfish requires highly oxygenated water with a medium to strong flow, but not overpowering.

A good strength of flow can be achieved with spray bars from a canister filter, angled towards the top of the water.

Powerheads with narrow gaps in the grill can also be used to create additional flow. We would advise that cages or guards (such as anemone guards) are used on powerheads to prevent entrapment/injury.

This species prefers a scape which includes an abundance of spaces in which it can hide, but the tank must also provided lots of areas of uncovered substrate to allow for wallowing (read substrate).

Water-logged driftwood and smooth boulders/rocks can be incorporated into the scape of the aquarium. Hardy epiphytes, such as Anubias and Java fern varieties, can be attached to the hardscape for decorative purposes and to provide additional areas of harbourage, but plants that need to be planted into the substrate should be avoided because the P.baileyi will disturb the roots.



The P.baileyi is an ambush predator and will spend most of its time lurking in-between the aquarium decor and wallowing in the substrate. This is how this species naturally hunts, awaiting any potential prey to come within striking distance. It is important that the Baileyi puffer is provided with a very soft, sand substrate for wallowing. A soft sand substrate should be considered an essential and not an optional extra. The Baileyi is a wallowing species and should always be afforded the provision of a substrate which allows it to exhibit its natural behaviour.

The depth of the sand should always match the depth of the fish's body. It is recommended to start as shallow as possible and gradually increase the depth as the fish grows. This fish will disturb the substrate on a regular basis by moving from place to place within the sand, but it is recommended that the keeper regularly stirs up the substrate to stop the sand from ‘compacting’ and to prevent the build-up of anaerobic bacterial populations.

Gravel and plant soil/substrate is unsuitable for the Baileyi and may cause injury if the fish attempts to wallow in it. Any sharp/course pieces should be avoided/removed.


Tank size

The tank should have a minimum footprint of approximately 80cm (31.5 inches) x 35cm (13.78 iches), with a height of 40cm (15.75 inches).

This translates to a tank volume of approximately 112 litres or 29.6 US gallons.


Water values

Maintain the following water parameters:

  • PH: 6.5 - 7.5 (in the middle is ideal)

  • Temp: 23-26°C (73.4 -78.8°F)

  • NH3/NH4+: 0ppm

  • N02: 0ppm

  • N03: below 15ppm

  • GH: 5-12 dGH



The P.baileyi is among one of the most aggressive pufferfish species. It will eat any fish that will fit into its mouth and will severely (often fatally) wound larger tankmates, so it is strongly recommended that they are kept as a solitary specimen.

The experienced aquarist may attempt to breed this species, but the behaviour between conspecifics is highly unpredictable.


Sexual dimorphism

It is claimed that mature males have more cirri.

However, the accuracy this method to determine the sex of individuals is yet to be confirmed.


Notable behaviour

P.baileyi is capable of metachrosis, meaning that it can voluntarily change colour to camouflage against its surroundings.

This species is known for its aggression and the aquarist must always exercise caution when their hands are in the aquarium. There have been many instances of these fish biting the preoccupied keeper during tank maintenance.

They are known to jump from the aquarium if startled, so they must only be housed in an tank with a tight-fitting lid.



One of the most important elements of keeping the P.baileyi is to provide a varied and balanced diet, in order to ensure that its nutritional needs are being met.

Our preferred foods for this species include:

  • Thiaminase-free fish meat, cut into manageable chunks (read feeding fish)

  • Gutloaded Earthworms

  • Gutloaded cockroaches, crickets and large woodlice

  • Repashy Grub Pie

This species should not be offered cockles, mussels, clams, oysters or similar mollusks.

The teeth of the P.baileyi do not grow as quickly as some other species of freshwater pufferfish, so the need to feed hard food items is greatly reduced.

Feed a ratio of 40% fish and 60% insects and worms. Owing to the inactive nature of this species, it does not require feeding daily. Three times a week is usually sufficient.


Feeding fish

Naturally, P.baileyi preys upon a very wide selection of different species of fish in the wild. For this reason, we recommend alternating between as many different suitable options as possible.

Frozen Pond Smelt (Hypomesus olidus) are widely available and they are small enough for the P.baileyi to eat whole. Pond Smelt is a common choice of food and bait, so it can typically be purchased from all well-stocked aquatic stores and bait suppliers. Some species of smelt such as Rainbow Smelt (Osmerus mordax) contain thiaminase (read Thiaminase), so it is important to ensure that you know what species of smelt you're buying.

Generally, the choices of suitable fish at fish counters and markets are going to be quite limited, but there are several common options.

Larger species of freshwater fish such as Lake Trout (Salvelinus namaycush) and various Tilapia species are suitable, but these fish are obviously too big for the P.baileyi to eat whole so they need preparing and cutting into manageable chunks. Discard of the internal organs, head and fins, fillet the fish and cut the fish fillets (scales and skin attached) into chunks small enough for the P.baileyi to eat within one minute. These pieces can be frozen and kept for up to three months.


Insects and worms

Gut-loaded insects and earthworms are excellent sources of nutrition for this fish and are used to replicate the gut-content of the P.baileyi's natural prey.

They are also ideal substitutes for freshwater crustaceans and are arguably far more nutritious than the saltwater crustaceans that most aquarists will be limited to at a fish counter/market.



Some fish and crustaceans contain thiaminase, which is an enzyme that renders thiamin (Vitamin B1) biologically inactive. This means that the pufferfish can not absorb any thiamin from that food.

Thiamin is a critical nutrient because it is an essential component of energy metabolism and it plays a key role in nerve, muscle, and internal organ function.

If a fish’s diet is mostly or completely made up of food items that contain thiaminase, that fish will develop a thiamin deficiency.

After consulting with veterinary professionals and other specialist keepers, we feel that avoiding foods that are known to contain thiaminase and replacing them with equally nutritious thiaminas-free food items is the safest, long-term option. This is the approach that we have taken with all of our pufferfish.


Feeder fish

We do not recommend the use of live feeder fish.

Feeder fish are often bred in squalid and overstocked conditions, where bacteria such as columnaris and mycobacteriums, and parasites such as Camallanus worms and Ichthyophthirius multifiliis (whitespot/ich) spread through the population very quickly.

Feeding feeder fish to your puffer greatly increases the chance of introducing pathogens to your aquarium, which can then infect your puffer and will require treatment. Feeder fish themselves are also usually nutritionally deficient.

Pao baileyi does not need live fish to thrive and will very often readily accept frozen-thawed food immediately after settling into the aquarium. The use of feeder fish can also cause piscivorous to become very finicky and they may start refusing anything but live fish. This is another reason that we strongly encourage you to begin the weaning process (read below) immediately.


Tips on offering prepared foods / weaning

Although some specimens will be reluctant to eat frozen-thawed foods at first, they can learn to accept it. The best training exercise is to offer nothing but live-earthworms to begin with and when your puffer is readily accepting those, start offering the same earthworms on forceps, building an association between the forceps/you and food.

When your pufferfish is accepting earthworms without hesitation from the forceps, you can then begin to offer other things, such as cockroaches, other insects and pieces of frozen-thawed fish. After several weeks, you won't need the forceps and your fish should readily accept any suitable foods that you drop into the tank.



This pufferfish is intolerant of poor water conditions, so a high level of biological and mechanical filtration is needed to deal with the amount of waste that this fish produces.

Adequate filtration combined with excellent husbandry is essential to the health of this species.

Frequent water changes must be carried out to maintain N03 (nitrate) levels below 15ppm.



Pao baileyi can inflate themselves when frightened or stressed.

They should never be provoked into inflating!


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