This weeks Fish of the Week is one that could be considered an old favourite that you will find in most good aquatic retailers and never seems to be the subject of the ‘fad’ or ‘latest trend’, they’ve always just been there; it’s the Astronotus ocellatus or more commonly (and affectionately) known as the Oscar, first described and named by the Swiss-American biologist Louis Agassiz in 1831 although he incorrectly identified it as a marine species!
Although often seen as small juveniles in aquatic centres, Oscars are fast growing and can easily obtain 35-40cm in length within 18 months. Oscars are usually dark brown or black (although you will sometimes see an albino form) in colour with red or sometimes yellow spots or ocelli. These ocelli, or eyespots, are thought to have evolved as a defence mechanism, giving the impression of a larger or even 2 headed fish to predators.
Oscars are native to large parts of South America including Brazil, Peru, Colombia and Ecuador where they are found in slower-moving regions of the Amazon and its tributaries as well as the Approuague and Oyapock rivers where they thrive in the relatively neutral waters. These neutral conditions; temperature 23-27°C, pH 6-8, KH 10-15dH are pretty easy to replicate no matter where you are in the country and maybe one of the reasons behind their enduring success.
Due to their adult size, Oscars will need a large, well filtered aquarium decorated with substantial pieces of rock and wood although even then oscars are known for their habit of re-arranging aquarium décor to their own tastes. For the same reason, only large robust plants such as Java fern, Amazon swords and species of the Anubias genus should be considered for an Oscar aquarium. Oscars can be kept with other large South American cichlids as well as catfish and members of the ‘pleco’ family, space allowing, but caution should always be taken, especially if you have a pair as they can become very territorial.
Oscars are not fussy eaters at all, in the wild they would feed on small fish, insects and crustaceans and this is what should be replicated with a good quality pellet food that is high in vitamin C, this can be supplemented with river shrimp and frozen cockle or muscle as well as the occasional algae wafer which oscars tend to enjoy.
One of the traits that has probably made oscars so popular with generations of fish keepers is their intelligence and ability to interact with their keepers. Oscars will follow you up and down the aquarium and can even be taught to hand feed, this has earned them another nickname amongst aquarists as ‘water dogs’, a trait which we feel more than qualifies the oscar as this weeks Fish of the Week.