The Amazon puffer (Colomesus asellus) is the odd one out in the family: a true freshwater, genuinely shoaling puffer that swims in open water all day rather than hovering in a corner. It is also sold as the South American puffer, bee puffer or Brazilian puffer, and it comes from the main channels of the Amazon and Orinoco basins. Keep it in a group, give it flow and length, and be ready for the fastest tooth growth of any aquarium puffer.
Amazon Puffer Care at a Glance
| Parameter | Value |
|---|---|
| Scientific name | Colomesus asellus |
| Adult size | 3–3.5 in (8–9 cm) |
| Lifespan | 8–10 years |
| Minimum tank | 30 gal for a group of five |
| Water type | True freshwater — no salt |
| Temperature | 72–82°F (22–28°C) |
| pH | 6.5–7.5 |
| Group size | 5 or more — genuinely shoaling |
| Temperament | Hyperactive, persistent fin-nipper |
Why Amazon Puffers Need a Group
Unlike almost every other puffer, Colomesus asellus shoals in the wild and behaves badly alone. A single Amazon puffer becomes nervous, hides and often stops eating; a pair pushes all the aggression onto one fish. Keep five or more. In a group the constant low-level chasing spreads out and no individual takes the brunt of it.
That group needs room: 30 gallons for five, and 40 to 55 gallons is better. Prioritise length — a 36-inch footprint minimum, 48 inches for a larger group.
Tank Setup and Flow
- Open swimming lanes. Structure along the back and sides, clear water in the middle.
- Moderate to strong flow. These are river-channel fish and they use current all day. A powerhead or a canister return aimed along the length works well.
- Driftwood and root tangles at the ends of the tank for retreat.
- Sand or fine gravel, and plants they will ignore rather than eat — anubias and java fern on wood.
- Filtration: 6–8× turnover, plus 30–50% weekly changes. Nitrate under 20 ppm.
Amazon Puffer Food and the Teeth Problem
Amazon puffers grow their beak faster than any other commonly kept puffer, so shelled food is not optional and even a good diet may not be enough.
- Daily staples: small snails, chopped cockle in shell, frozen bloodworms, mysis, brine shrimp.
- Feed daily — this is an active fish with a fast metabolism.
- Expect to check the beak. Many Amazon puffers need trimming every four to eight months regardless of diet. See the teeth and trimming page.
- Watch the fastest eaters. In a group, one or two fish take most of the shelled food; spread it across the tank.
Amazon Puffer Tank Mates
Their own kind first. Beyond that, Amazon puffers are relentless nippers — a slow or long-finned fish will be stripped. Where mixed tanks work it is usually a large, high-flow South American setup with fast mid-water fish that keep clear:
- Possible in 55 gal+: large fast tetras, silver dollars, hoplo catfish, larger loricariids that stay under wood.
- No: angelfish, gouramis, bettas, guppies, corydoras with long barbels, all shrimp and ornamental snails.
Check any pairing with the compatibility checker, and see the tank mates guide.
Health Notes
- Wild-caught by default. Quarantine for four weeks and deworm with praziquantel and metronidazole on arrival.
- Nitrate sensitivity. As an active fish in a group, it shows chronic nitrate as faded colour and reduced activity before anything else.
- Half-dose medication. Scaleless, like every puffer.
- Beak checks every few months — catching overgrowth early avoids sedation.
Frequently Asked Questions
What size tank does an Amazon puffer need?
Thirty gallons for a group of five, with 40 to 55 gallons preferred. Length matters most: a 36 inch footprint is the minimum and 48 inches suits a larger group, because these are open-water river fish that swim all day.
Do Amazon puffers need to be kept in groups?
Yes. Colomesus asellus is one of the few genuinely shoaling puffers. A single fish becomes nervous and often stops eating, and a pair concentrates all the aggression on one individual. Keep five or more.
What do Amazon puffers eat?
Small snails, chopped cockle in shell, frozen bloodworms, mysis and brine shrimp, fed daily. Shelled food matters more for this species than any other because it grows its beak faster than any other aquarium puffer.
Are Amazon puffers freshwater?
Yes, genuinely. Colomesus asellus lives its whole life in the fresh water of the Amazon and Orinoco basins and needs no added salt, unlike green spotted and figure 8 puffers.
What tank mates work with Amazon puffers?
Their own kind first. In 55 gallons or more, fast mid-water fish such as large tetras and silver dollars sometimes work. Angelfish, gouramis, bettas, guppies, shrimp and ornamental snails do not, because Amazon puffers are persistent fin-nippers.
How often do Amazon puffers need their teeth trimmed?
Many need it every four to eight months even on a diet full of shelled food, because their beak grows unusually fast. Check the mouth every few months and correct the diet early rather than waiting for the fish to stop eating.