The oscar (Astronotus ocellatus) is sometimes described as the velvet cichlid, because of its very small scales, which give its body a velvety appearance. The eyespot usually present near the base of the tail means this fish has also been called the peacock cichlid. It was first described in scientific literature in 1831, and then became popular as a pet in second half of the 20th century, although it had been valued as a food fish in its South American homeland for centuries beforehand.

Housing

Obtain a large aquarium, at least 120cm long x 45cm high and wide for a young pair. Oscars grow big and mean, with smaller tankmates simply likely to disappear on a dark night! These cichlids can grow to a tank-busting 35cm, so be prepared.

Care

A power filter as well as an undergravel filter will be needed, as oscars are messy fish. They will dig through the aquarium gravel with their jaws, in search of anything edible, and uproot plants at the same time. Aquatic vegetation therefore either needs to float or should be weighed down. Their food should consist of cichlid pellets combined with treats such as the occasional thawed prawn, pea or canned cricket. Young fish prefer special flake food.

Temperament

Assertive but friendly towards people. They will recognise you, and will be waiting for a meal if you feed them at set times every day. Pairs are devoted to each other, forming what can be a lifelong bond while they are still young. Trying to introduce two adult oscars can be tricky though – they may disagree violently. It is always better to obtain a compatible pair, if not young fish.

Varieties

The oscar’s basic ‘wild’ coloration is greenish-brown with reddish markings, while young oscars have a striped patterning. Selective breeding has created the much more colourful red tiger. Here the red coloration is very evident and arranged in an abstract striped pattern, with some individuals being much more colourful than others. You can also choose from albinos, with white bodies and variable orange markings, plus rarer yellowish lutinos, as well as long-finned variants of these colours too.

Did you know?

Pairs are devoted parents, cleaning their chosen area of rockwork carefully, with the female then laying up to 3000 eggs here. These should hatch after just 36 hours. Both parents then watch over the young fish at first, which grow rapidly. They can already be 5cm long at just 3 months of age.

Lifespan

Up to 10 years or so.

Likely illnesses

Oscars are vulnerable to hole-in-the-head disease, caused by a microscopic parasite called Hexamita. Stress (perhaps linked with overcrowding) and possibly vitamin deficiencies too may be contributory factors. The result is likely to be permanent scarring on the face, assuming the fish survives, with successful treatment being possible. Pimples on the forehead are an early sign, which then broaden out into patches.

Equipment needed

Aquarium with hood and light, water conditioner, suitable filter – power filtration essential for larger oscars. Cichlid pellets and livefoods, especially worms, both prepared and fresh. A robust heaterstat – wattage based on water volume in the aquarium – with a heater guard if needed, and a thermometer. Water test kit to ensure water quality, plus a net will also be required.