Fat oscar

Care at a glance

Overview

This is the southern cousin of the common oscar, with the same big personality and a moodier, darker coloration, and it is kept as a single fish or a bonded pair rather than a group. It fills the middle and lower water and, like all oscars, rearranges the tank to suit itself. It is large and aggressive, so pick tankmates with real care: only big, robust fish that can hold their own, and expect it to eat anything small. Feed a varied diet of large sinking pellets, mussel, prawn, earthworm and other meaty foods, avoiding a steady diet of feeder fish. A single oscar needs a tank of at least 500 liters with strong filtration and few breakable furnishings.

In the wild

Astronotus crassipinnis comes from the southern reaches of the Amazon and the Paraguay and Guapore basins, living in warm, slow backwaters over sand, mud and sunken wood. Recreate that with a soft substrate, big pieces of driftwood and open swimming space, without delicate plants it would only uproot. Keep the water soft to neutral, roughly 23 to 28 C at a pH from 6.0 to 7.5, with strong filtration for a big, messy fish.

Good to know

In the family Cichlidae, this is the southern oscar, reaching around 29 centimeters, darker and thicker-finned than the common Astronotus ocellatus; its name, crassipinnis, means thick-finned. It is a biparental substrate spawner that lays eggs on a cleaned surface and guards them, but getting a compatible pair and a successful spawn from these headstrong fish is a hard task.

Did you know

Its range reaches well south into the Paraguay basin, subtropical country that cools far more in winter than the warm equatorial waters the common oscar calls home.

Common questions

Related species

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