The Fun, Friendly, Freshwater Amazon Puffer

Author: Rebecca Goldring

I first encountered the Amazon pufferfish in 2014 after seeing them on an import list from a local aquatics vendor, who advertised them as being suitable for a community tank. While I didn’t know anything about them, I was intrigued by the idea of a puffer that could fit in to a peaceful South American community, especially since most pufferfish have a reputation for being anything but peaceful.
Puffers are charming and entertaining fishes that exhibit several characteristics humans find endearing, even cute. Amazon puffers are no exception, with their big googly eyes (which move independently), rounded shape, goofy grins, and a knack for swimming like drunk bumblebees. They are what some would call “derpy,” in a good way. While I wouldn’t describe them as conventionally beautiful, their bright yellow-green and black-banded bodies with cream undersides and fluttering fins make them an attractive fish nonetheless. 
The Amazon puffer, also known as the South American or friendly pufferfish, is a relatively small freshwater puffer found primarily in Brazil, but also in other areas throughout the Amazon River basin. This shoaling behavior is what often earns them the common name “friendly puffer” and, unlike many of their cousins, these fish are happiest in groups—the more, the merrier! They do seem to enjoy playful interactions and, on several occasions, I’ve witnessed them engaging in “barrel rolls” and other apparent play behaviors in larger groups.

Species Identification

While all Amazon puffers are exported and sold as Colomesus asellus, a second distinct species, C. tocantinensis, was identified in 2013 via some very science-y science (DNA analysis). While C. asellus is found throughout the Amazon, C. tocantinensis seems to be restricted to the upper drainage of the Rio Tocantins. These two species are visually indistinguishable to the home aquarist and have the same basic requirements. While knowing the collection point of your fish might help you guess at a species ID, there’s no way for the average hobbyist to be certain which species they’re keeping.
A third species of Colomesus, C. psittacus or the “parrot puffer,” is occasionally confused with C. asellus when very young. The parrot puffer grows far larger than either of the other Colomesus species, however, and does not regularly demonstrate shoaling behavior in adulthood like its friendly cousins. 

In the Aquarium



These freshwater puffers appreciate a bit of current and good aeration in the aquarium. Like many wet pets, they are sensitive to deteriorating water quality and should not be kept in immature or poorly maintained aquaria. Ensure your tank has adequate filtration and surface movement. This is especially important because the high temperatures these fish thrive in make it more difficult to keep water well oxygenated. 
In tanks with directional flow from a powerhead, I often catch them racing up and down in areas where currents hit the glass, or surfing cross currents. In one tank, the fish virtually lined up to get shot across the tank by the spray bar, one at a time, and then would circle back for another ride. That said, they are not strong swimmers and I’ve had perfectly healthy fish wander too close to the intake of a high-powered filter and get stuck. 
As fish go, these guys seem pretty intelligent. I’ve caught certain specimens engaged in behaviors that my human brain can’t help but interpret as games. I had one group that would swim in repeated circles around my magnetic algae scraper, no matter where in their tank I had it parked. One fish would start the game and gather others to engage in the same behavior. 
They are also highly social with each other and even, occasionally, other fish. Years ago, I had one particular individual who befriended a lone geriatric tetra and spent all day every day following the tetra around, despite the presence of other puffers in the tank. 
These fish are undeniably cute, and they often interact with their keepers. Once settled in, Amazon puffers are not at all shy, and they quickly figure out where the food comes from. They also learn to take advantage of their cuteness and will quickly perfect the art of begging for food, readily recognizing which of the humans outside their tank are most likely to cave in and provide treats.
Early on in my Amazon puffer keeping, I learned—the hard way of course—that they are ich magnets. Pufferfish do not have scales and, while some varieties handle a wide range of temperatures, Amazon puffers like it warm. I keep mine at between 82° and 86°F (28° and 30°C). Whenever I bring them home, I will quarantine them for a minimum of three weeks and treat them as if they have ich. Even if they don’t have spots at the shop, odds are they will within a few days. 
Newly acquired Amazon puffers go into a tank that’s at least 86°F (30°C), and I treat them with an ich medication that is safe for scaleless fish. After this treatment, I drop the temperature gradually and watch them for at least one additional week to ensure no signs of ich develop. Due to their susceptibility to ich, I recommend keeping them in well-heated tanks and taking care to prevent wide temperature swings during water changes.
These are an Amazon fish, and so they come from tropical freshwaters. I’ve found that they’re pretty adaptable, but they really do best in the fairly soft, acidic water that is typical for most Amazon fishes. One of the problems I’ve seen with getting them from some fish stores is that, like many aquarists, they see “puffer” and think “brackish,” and put these guys in tanks with lots of salt. These freshwater puffers don’t do well with salt, not even as an ich treatment. Keep them warm, and in clean, soft, acid water. 




I also quickly learned that feeding them both is and is not problematic. They have fast metabolisms and, despite always being wild caught, they readily accept all types of food once they’ve settled in. It doesn’t take long without food for Amazon puffers to look starved, particularly if they’ve arrived a little lean. When a group is new, they should be fed live or frozen foods multiple times a day and watched to ensure all individuals are eating. 
An Amazon puffer in good condition will look smooth and round bodied, even if they have not eaten recently. While all puffers will “fill out” to some extent after eating, a healthy puffer will never look thin, angular, or empty. Like other pufferfish, Amazon puffers will gorge themselves almost any time they get the chance. The end result can be pretty comical, and not particularly hydrodynamic. 
A willingness to accept a variety of foods makes Amazon puffers easy to feed, but also means they quickly learn what is easiest to eat. The downside of this is that most prepared and frozen foods do not offer enough “crunch” to keep their fast-growing beaks trimmed, and overgrown beaks make it hard to eat. 
While supplementing other foods with shrimp and snails can help, many keepers find they need to occasionally trim their puffers’ beaks. The process typically involves an anesthetic (e.g., clove oil) and a decent pair of cuticle clippers. A quick web search will turn up a variety of results on how to do this, but my preferred tutorial, Jeni Tyrell’s “Small Puffer Dentistry,” can be found at


So, are these friendly puffers really friendly enough to keep in a community tank? It depends. Most groups I’ve had left other fish alone and got along swimmingly with tankmates. I’ve even kept one group, rather successfully, with discus. They don’t bother plants at all, and they can do a reasonably good job at snail control.
That said, Malaysian trumpet snail shells are too hard for their beaks, and they do sometimes get lazy about snails when there’s plenty of other food available. In heavily planted tanks, I’ve actually had shrimp colonies survive with a group of Amazon puffers. Overall, they seem to fare well with peaceful cichlids, catfish, and other community fish, provided they are not outcompeted for food. 
As with all puffers, I don’t recommend keeping them with fish that have very long, flowing fins. I’ve had more successes than failures keeping them in peaceful community tanks, but failures do happen.
At the end of the day, despite their “friendly” moniker, don’t count on keeping Amazon puffers with other fish species. As with many fish, what is true for any particular group or individual isn’t always true of others. 
The most recent group of Amazon puffers I acquired could not live with other fish. While this particular shoal was friendly within species, everything else in the large tank I added them to was pestered and fin-nipped to the point of severe stress, no matter how well fed the puffers were. Even large loricariids, fast-moving tetras, and heavily armored catfish had rounded nip-marks along their bodies and at the edges of their fins. 
The puffers were well fed with a wide variety of prepared frozen, home-made frozen, dried, and live foods, but they still had a taste for fins and scales. I had to remove that group from their community tank, and eventually rehomed them. If you hope to keep a shoal of these in a community tank, have a “plan B” ready, and make sure you have time to observe their behavior regularly so that you can remove them if their behavior begins to negatively impact tankmates.
If you do need to move your Amazon puffers, take care to ensure they stay submerged throughout the process. As with other types of pufferfish, these freshwater puffers will inflate when they feel threatened. If pufferfish inflate outside of the water, they take in air instead of water and can end up with air trapped in their body cavity. When this happens, it interferes with their ability to swim, stay upright, and eat. If a pufferfish cannot clear trapped air from their body, they will eventually die. The best way to move puffers is by scooping them into a cup or transferring them from a net to a cup while they are underwater.

Adorable Oddballs



Amazon puffers are one of those oddball fish not likely to be found at a run-of-the-mill pet shop. Even in the best aquatics shops, their availability is usually seasonal. Despite being charming and completely adorable, some of their quirks probably deter folks from keeping them at all or trying again after an initial failure. 
Another possible deterrent is price. These are schooling fish, which means they really need to be kept in groups, and purchasing even just a small school of them can be expensive. They demonstrate their most interesting behaviors in larger groups and can become bored and depressed when kept singly. If you’re interested in this fish, investing in a school of them is well worth it. 
One of the most daunting things about investing in fish less commonly kept is a general lack of available information about them. While some information on C. asellus is readily available via the internet, the quality and validity of some online information is questionable. While I cannot claim to be an expert on keeping Amazon puffers, I’ve spent a considerable amount of time living with and learning about them. Hopefully fish and fishkeepers alike can benefit from my experiences. 
Overall, I’ve found C. asellus a rewarding species to keep. Even friends and family who “don’t get” my fish hobby find themselves drawn to these fish and are entertained by their antics. I’ve found them to be fairly hardy and unfussy fish, provided they are kept at an appropriate temperature. I’ve even learned how to trim their beaks when needed. 
Outgoing, active, and curious, Amazon puffers are a worthy addition to most collections, especially if your luck holds and you find a group that can be kept in a community tank.