Food Items: Insects and insect larvae, crustaceans and other invertebrates (such as crayfish and worms), fish, and various plant matter. However, being opportunistic, just about anything that will fit in their mouth they wll eat. This nature causes them to always act hungry, even if they are being well or even overfed. Overfeeding and resulting health issues is fairly common in the hobby because of this.
Longevity: Oscars can live for well over a 10 to 15 years. Success with these fish is measured in years, not months. These fish are a long term commitment that should not be taken lightly. Temperament: Oscars are mildly aggressive. They have a rumored vicious nature, but that just isn't the case. This rumor is derived from the fact that they are many times willing to attempt to eat anything in the tank they think will fit in their mouth. In all reality, the are pretty mellow compared to other cichlids, and are many times bullied by other more aggressive cichlid tankmates. They are territorial though, and a breeding pair may become highly aggressive towards tankmates when spawning. Also, providing too small of an aquarium can cause two Oscars in the same tank to constantly fight, sometimes to the point of being fatal.
A Brief Overview: Oscars are extremely intelligent fish capable of being conditioned to do many little tricks. They quickly learn to recognizing those that feed them and reacting accordingly (usually begging for food). They have a unique presence, intelligence, and attitude that makes owning them a true joy to those that love them. This combined with the fact that Oscar can live just as long as a dog makes them more like a pet than most other fish could ever be.
Tricks: These intelligent fish can learn to roll over for food. They can beg for food and understand how you feel. If you stick a ping pong ball in the tank they will move it around. If they don't like something in the tank where it is they will pull it up and move it around. If you feed them feeders (gold fish) sometimes they will mess with them, sometimes they will eat them then spit them out and catch them again. They can also be petted if they are used to you. But don't do this all the time because you can ruin their skin.
Temperature: 72F/23C to 85F/29C pH: 6 to 7.5
Single oscar should have a 30 gallon tank or more. Two oscars should have a 75 gallon or more. Tank mates:
Firemouth Cichlid: This is a good tank mate for oscars. They only get 6 in. max but the oscars usually can't swallow a fish that big. If you want a Firemouth raise him and the oscars together from when they are small.
Convict Cichlid: These fish are highly aggressive but are small 5 to 6 in. max which makes them good with oscars.
Pacu: If you want a piranha type fish then this is the closest to the real thing but be careful not to get a red belly pacu this type has a full set of teeth and are to close to the real thing. But beware they get big even bigger than oscars. A tank of at least 500 gallons will be needed.
Jack Dempsy: Now if you have two or more oscars and they are bigger than the Jack Dempsy than they should be fine. So make sure you follow these rules with Jack Dempsys because if your other fish are smaller the Jack Dempsy will probably kill them.
Texas Cichlids: I don't really know much about these fish but I have heard that they make great tank mates.
Large catfish: Oscars and catfish that are Large never bother with each other. Except for Shovel nose catfish which get about 3ft. long they may be able to eat an oscar. Normaly to big for aquariums under 500 gallons.
Health Problems: Hole in the Head Disease, or HITH, is a form of lateral line erosion disease. Normally healthy Oscars have a number of small holes around the area of the eyes, and along the lateral line. These holes become more pronounced as the oscar ages. They are perfectly normal, and should not be confused with HITH.
Normal Sensory Pits:
HITH starts out as small erosions in and around the sensory pits. These erosions appear as small grey-white patches in the area of the head above the eyes.
Early Stage HITH:
As the condition progresses, the grey-white patches will increase in size and number.
Eventually, noticable pits develop.
If the area becomes infected, the areas may develop red streaks and puss may be present in and around the sores.
This condition is caused by poor water quality and/or poor nutrition. It can be easily cured, particularly if caught in its early stages by increasing tank maintenance to improve water quality, making sure the oscars are fed a balanced diet, and by dosing the food with multivitamins.
While parasites such as Hexamita may be present in the sores, they are there on an opportunistic basis, and are not the cause of the condition. If your Oscar shows symptoms of parisitic infection, that infection should be treated by apropriate means.