Information about this Amazon River cichlid.
The Oscar (astronotus ocellatus) is a member of a family of fish called cichlids. Also called velvet cichlids, marble cichlids or tiger Oscars, in nature they are primarily found along the Amazon River Basin. The Oscar is native to several countries in South America, including Peru and Brazil, though they have been accidentally introduced into other countries now, including the U.S. and China. Oscars naturally prefer warmer water, with a lot of nutrients, a slow moving current, and some vegetation for cover.
An Oscar’s body shape is almost identical to the shape of a human eye, with the inner corner corresponding to the head of the fish. The tail and dorsal fins of the fish often enhance this similarity, as they fit together and often appear much like a drawing of thick black eyelashes surrounding the back two-thirds of the fish. The Oscar typically has short pectoral fins just behind and slightly toward the bottom of the gills. Oscars are about twice as long as they are tall, not including the tail, and very stream-lined, remaining flat and about the same thickness, from their heads to the base of their tails. The eyes are on the sides of the head, but rather close to the mouth, which opens at the top and therefore gives the appearance of a severe frown. The typical Oscar is dark brown or nearly black, with red marbling over the body and sometimes the fins. With selective breeding this marbling may vary from barely any red to barely any black showing, and other marbling and base colors may occur including yellow, orange and white – or even pink. Some ornamental Oscars also have been bred to have long fins much like a veil tailed goldfish. Regardless of color or fin length, though, the face and the shape of the body stay pretty much the same.
Oscars are extremely hardy fish in an aquarium setting. They can and will adapt to a wide selection of water chemistries, with pH from 6.0-8.0 and dH anywhere from 5-19. In addition they will eat many types of food, from basic cichlid pellets to insects to small feeder fish. Because they can grow so large and also because they so enjoy to rearrange items in the tank, Oscars are best kept in tanks which are at least 75 gallons and have a really good water filtration system. These fish should be kept in warmer water temperatures (72-77° F) and only with fish which are as large as the Oscar or larger, so that the other fish do not get mistaken for food and eaten. With fish their size or bigger, Oscars are considered to be non-aggressive. They enjoy some cover plants and other items which they can move around the tank at will. If the intention is to try to breed them, it is recommended no other fish are in the tank and that there is a large rock with a flat surface, either vertical or horizontal, on which they can lay their eggs.