Updated: Dec 17, 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.
The main priority at Pufferfish Enthusiasts Worldwide will always be to provide the most accurate and up to date information pertaining to individual species of pufferfish 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 with the care sheets for SEO reasons. We realise that most people are not going to search "Colomesus asellus care" and are instead more likely to search for "Amazon puffer care", so this care sheet is going to refer 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.
The asellus is a species of freshwater pufferfish, from the Colomesus genus, which is endemic to tropical South America.
This C.asellus is a very popular aquarium fish and is commonly referred to as the Amazon Puffer, Peruvian Puffer and the South American Puffer (sometimes abbreviated to SAP).
Owing to the convenient size and social nature of this pufferfish, it has become very popular with keepers across the world.
Despite this species being one of the most common pufferfish in captivity, the internet is still plagued with erroneous information and most care guides completely fail to recognise that this species is in fact a shoaling fish, or recommend unsuitable foods which may be very unhealthy for the fish over the long term and tanks that are too small. Unfortunately, the more common a species is, the more folklore seems to surround them. Pufferfish Enthusiasts Worldwide intends to set the record on this species straight.
In the wild
The distribution range of Amazon puffer includes the Tocantins River basin, as well as numerous other rivers in South America.
In the wild, this species eats a variety of insecta, but almost half of their diet is comprised of Ephemeroptera nymphs (known as mayfly, fishflies and shadflies). Gastropoda (snails) make up just over a quarter (25.07%) of an adults natural diet and around 6.5% of a juvenile's diet. They also eat Chironomidae (known as non-biting midges), other insects, gastropods (snails) and plant/algae matter.
In the aquarium
The Amazon puffer is prized for being "friendly" and is commonly referred to as the "community puffer". While it is true that the Amazon puffer is, by far, one of the friendliest species of freshwater pufferfish, they are not perfectly peaceful and we will discuss this further within the section on tank mates in the care sheet (below).
Amazon puffers are intelligent fish who need lots of stimulation and social interaction with their own kind.
You can give an enriching aquarium by providing an elaborate scape with lots of caves and hiding spaces to explore, but keep in mind that they are very active swimmers so they should always have plenty of open swimming space too.
We recommend heavily scaping the back of the tank with plants and hardscape materials, while leaving open swimming space at the front, which will encourage the fish to swim the length of the aquarium where you can watch them. A heavily decorated tank will help the shy, yet active Amazon puffer feel secure and contained, knowing that they can take cover quickly if they need to, which will result in more natural foraging and explorative behaviours.
Amazon puffers appreciate highly oxygenated water with a medium to strong flow, which they enjoy swimming against. The strength of the flow in the aquarium is usually achieved with spray bars from canister filters, angled towards the top of the water. Keeping a slightly dropped water level so that the returning water from the filter splashes down onto the surface creating agitation and facilitating a gas exchange for high levels of oxygenation.
Powerheads with narrow gaps in the grill may be used to create additional flow. We would advise that cages or guards (such as anemone guards) are used on powerheads to prevent injury to the fish if they be