Colomesus psittacus

Lore & Background

Colomesus psittacus inhabits the Western Atlantic coastline of South America, ranging from the Gulf of Paria to the mouth of the Amazon River in Brazil. Its coloration is green above and white below, patterned with black transverse bands across the dorsal surface. Compared to the related Colomesus asellus, the black bands on the back are much thinner, and it lacks a distinctive black band that rings the base of the caudal fin. This species grows to a length of 28.9 cm SL.

The species is euryhaline, moving freely between freshwater and the sea. Its natural diet is carnivorous and consists mainly of molluscs. In the aquarium, it eats a variety of invertebrates including snails, clams, and shrimps. Like other pufferfish, it has the ability to inflate itself when threatened, making itself much larger and more difficult for predators to handle or swallow.

The flesh of Colomesus psittacus is edible, but its liver is toxic. Whether the toxin is saxitoxin or tetrodotoxin, as is the case with many marine puffers, is not known.

Reader's Guide

Colomesus psittacus is rarely kept in home aquaria due to its large size and need for salt water. In terms of maintenance, it is otherwise similar to Colomesus asellus. It is not a schooling species and may be aggressive towards others of its species, so it is usually kept alone. Its significance lies in its distinctive banding pattern and its euryhaline ecology, which allows it to inhabit both freshwater and marine environments along the South American coast. The uncertainty regarding the specific toxin in its liver—whether saxitoxin or tetrodotoxin—highlights the incomplete knowledge of its biochemistry. Despite its edible flesh, the toxic liver means that consumption carries risk. The species' ability to inflate as a defense mechanism is a characteristic shared with other pufferfish, contributing to its survival in estuarine and coastal habitats.

Did You Know?

• It lacks the black band at the base of the caudal fin that is present in Colomesus asellus.
• The species can inflate itself when threatened, making it harder for predators to swallow.
• Its liver is toxic, but whether the toxin is saxitoxin or tetrodotoxin is not known.