Amazon puffer

Colomesus asellus

Also known as South American Puffer

FreshwaterFish

Amazon puffer (Colomesus asellus) — O. Schneider · CC BY-SA 3.0

Care at a glance

Temperature: 72–82°F; 22–28°C
pH: 6.0–7.5
Adult size: 4.7 in; 12 cm
Minimum tank: 26 gal; 100 L

Temperament: Mostly peaceful
Social behavior: Shoaling
Tankmates: With caution
Swim level: Middle
Difficulty: Difficult
Breeding: No record
Rarity: Rare
Family: Tetraodontidae
Origin: Brazil, Colombia, Peru, Ecuador

Overview

Unusually for a puffer, the Amazon puffer does best in a group and turns nervous when kept alone, so plan on a small shoal of five or more. They are active, busy swimmers that spend the day cruising open water rather than lurking. They can be nippy, so keep them as a species group or only with fast, robust tankmates, and watch for fin-nipping. Their teeth grow constantly, so a steady diet of hard-shelled prey is essential. Feed pond and ramshorn snails, small clams and mussels, and frozen shrimp to wear the teeth down. A group needs plenty of swimming room, so aim for a tank of around 100 liters or larger.

In the wild

The Amazon puffer is a true freshwater fish from the large river systems of Brazil, Colombia, Peru, and Ecuador, where it roams flowing channels and follows the seasonal floods. Unlike many brackish puffers, it never needs salt. Give it clean, well-oxygenated water with a gentle to moderate current, a pH between 6 and 7.5, and a temperature from 22 to 28 C. Open swimming space matters more than heavy decor, but include driftwood and some planted areas along the sides so the group has room to patrol the middle of the tank.

Good to know

The Amazon puffer belongs to the family Tetraodontidae, the true puffers, whose four fused teeth form a hard, beak-like plate. Adults reach about 12 cm. Like all puffers it can gulp water to inflate into a ball when threatened, and it lacks scales and normal ribs. This species is famous for having some of the fastest-growing teeth of any freshwater puffer, which is why hard foods are not optional. Aquarium breeding is essentially undocumented, and almost all fish in the trade are wild caught.

Did you know

The Amazon puffer grows its beak-like teeth faster than almost any other freshwater puffer. Without a constant supply of snails and other hard-shelled food to grind them down, the teeth can overgrow until the fish cannot eat, and keepers sometimes have to trim them by hand.