Pufferfish are what we refer to as ‘oddballs’ in the aquarium hobby: they don’t fall into any of the regular fish categories. Colomesus asellus, also known as the Amazon puffer, is even more of an oddball than other puffers. Unlike its very aggressive cousins, that should always be kept alone, it loves the company of its own species and can even be kept in some types of community aquariums. Not a fish for beginners, but the perfect choice if you’re looking for an unusual species that few other aquarists keep.
Keep reading for everything you need to know about Amazon puffers and keeping them in your own aquarium!
Colomesus asellus, also known as the Amazon puffer, South American puffer (SAP) or assel puffer.
|Tank size||47" (120cm) minimum|
|Temperature||71.5-82.5 °F/22-28 °C|
Colomesus asellus natural habitat
As its common name suggests, the Amazon puffer is naturally found in the Amazon basin and a few surrounding areas. Here, it doesn’t inhabit a specific habitat type: this puffer is found in all kinds of fast-flowing waters with or without vegetation. The water can be soft and acidic or harder with a higher pH.
Colomesus asellus appearance
With a maximum size of around 8 cm (3.1 inch) Amazon puffers are one of the smaller puffer fish species available in the aquarium trade. Beginners might have some trouble distinguishing Amazon puffers from different puffer species, especially when the fish are juveniles. Many have white bellies and yellow-green backs, but luckily they all sport a different pattern. Amazon puffers will have five stripes running across the top of their body: one above the eye, one behind the eye, one behind the pectoral fin, one under the dorsal (back) fin and one ring right before the caudal (tail) fin.
One puffer that’s especially similar to the Amazon puffer is its cousin Colomesus psittacus, which is a brackish puffer that grows much larger. It can be told apart by its extra back stripe, smaller eyes and larger size. It’s also not a very popular aquarium puffer so you’re unlikely to come across it in the average aquarium store.
As with most puffers, it’s not possible to tell the difference between male and female Amazon puffers.
Colomesus asellus requirements
Note: Like almost all puffer species, the Amazon puffer is not a beginner fish. If you’re a beginner interested in keeping puffers consider going for a dwarf puffer instead.
- Tank size. Amazon puffers are very active fish that should be kept in groups of at least three. They are also very messy eaters. This means they need a relatively large tank, both in volume and footprint: go for an aquarium of at least 47″ (120cm) to keep them happy and healthy in the long run.
- Water quality. A crucial point in puffer keeping is water quality. Amazon puffers don’t care much for a specific hardness or pH and do well in a relatively wide range of temperatures, but what they absolutely cannot handle is bad water quality. This means your tank should always be fully cycled and without the slightest trace of ammonia or nitrite. Nitrates should be kept low as well, which means weekly water changes are in order. One or more powerful canister filters are needed, as these puffers are very messy eaters and decaying food bits quickly foul the water. Be sure to do regular water tests using a liquid test kit, even if you think the water quality is fine. Better safe than sorry!
- Decorations. Like all puffers your Amazon puffers will love a well-decorated tank with plenty of places to explore. An ideal Amazon puffer setup will have lots of plants, driftwood, rocks and maybe even some leaf litter to explore while still maintaining enough open space to swim. Because these puffers naturally inhabit habitats with relatively strong currents and well-oxygenated water it’s a good idea to position your filter outflow so that they can swim against the current. You can also consider an extra powerhead.
Colomesus asellus tankmates
Amazon puffers are sometimes referred to as ‘nice puffers’ because they are one of the only larger puffer species that will tolerate some tankmates. They are also the only species that should be kept in groups and will display signs of stress when kept alone. Get at least three Amazon puffers; more is better!
Despite their ‘nice’ reputation, Amazon puffers are not suitable for regular community aquariums. They don’t view other fish as food but are still notorious fin nippers that can cause stress among their tankmates. A single-species setup is probably still the best idea. If you do want to keep your Amazon puffers with other fish go for quick species with short fins or species that spend most of the day in hiding. Corydoras are a good example of a sturdy fish that should be quick enough to avoid nippy Amazon puffers, but keep in mind that they might still end up missing some fin chunks now and then.
Colomesus asellus diet
One of the most important aspects of keeping any puffer and especially Amazon puffers is their diet. Amazon puffers are omnivores that naturally eat snails, shrimp, aufwuchs and anything wiggly such as mosquito larvae and worms. In the aquarium their diet should consist mostly of hard, crunchy foods like ramshorn snails, crab legs and small mussels or cockles. You can also occasionally feed live or frozen foods such as mosquito larvae. Pellet foods might be an additional option – some Amazon puffers will accept algae pellets.
Sticking to these diet rules is important because puffer teeth keep growing throughout their life and the only way to wear them down and keep them from overgrowing is by offering hard foods. Even then Amazon puffers are known to be especially prone to overgrown teeth and you might still need to trim their teeth occasionally. You read that right: trim their teeth. This is usually done by sedating the puffer using a very small amount of clove oil and trimming off a tiny part of the teeth using cuticle clippers. A puffer with overgrown teeth is unable to eat and will starve, so be sure to always keep a close eye on those chompers.
A snail breeding tank is a must for any puffer keeper. You can read more about breeding your own snails here.
Colomesus asellus behavior
Puffer fish are pretty difficult to keep and very sensitive. The reason they’re still very popular in aquariums is their behavior. All puffers, including Amazon puffers, are intelligent, inquisitive and fun to watch. They will closely inspect anything that enters the tank or gets close to it using their big, curious eyes that can move independently. They seem to hover instead of swimming and quickly learn to recognize their owner. Amazon puffers are naturally migratory, which means they are very active and will constantly be swimming, inspecting things and surfing the filter flow.
Because Amazon puffers are so intelligent and active they do need a lot of enrichment. If you frequently spot your Amazon puffers ‘glass surfing’ your tank might need some extra decorations or stronger water flow. Try tall plants like Vallisneria to easily break sight lines!
Breeding Colomesus asellus
Amazon puffers have never been bred in the aquarium. The eggs are very small and no parental care has ever been observed. The fry seem to go through a planktonic phase before growing into ‘real’ fish, which makes raising them in the aquarium pretty much impossible.