There are many things to consider when adding Oscar fish to a fish tank. Here are some of the top ones. One of the most important things to consider is tank size. Since each fish can quickly grow to 12-16 inches and up to 3 1/2 pounds, a large tank is a top priority. Because of their large size and density the typical one gallon of water per inch of fish does not work. Oscar can also grow an inch or more per month. This means getting a large tank to begin with is much less expensive and a lot easier on the fish than getting multiple tanks as the fish grow. Generally, it is best to get a tank at least four times as long as the fish is likely to grow to as an adult. Therefore, if your fish will grow to be 12 inches, you would want to make sure the tank is at least 48 inches long. This will give the fish enough room to keep it healthy and give it enough exercise to keep it happy as well. The tank also needs to be wide enough that the fish tank fish does not need to bend itself to turn around.
Since they are territorial fish, Oscar fish tanks need to be a bit larger length and width wise rather than height wise. This is because each fish needs its own personal space, which is measured in inches rather than volume of water. Without its own space, the Oscar will fight with any tank mates, sometimes to the death to create its territory. With the large size they grow to, Oscar tend to need at least three square feet of territory per fish. If you are going to have very many fish, you will need a huge tank. For one fish, a 55-gallon tank will work but bigger is better when it comes to these fish.
The next important thing to consider is filtration. Oscar are messy fish, which requires massive filtration in order to keep the tank clean and the fish healthy. Many fish keepers recommend having two types of filters, that way if something happens to one you have a backup. The most common fish tank filter is one that hangs on the back of the tank (HOB). With HOB filters, it is recommended to have one that will cycle the entire volume of the tank ten times per hour. Aquarium canister filters are also common, sometimes used with the HOB filters. With these, it is recommended to have on that will cycle the tanks entire volume four times per hour. Eheim, Aquarium, Aqueon, and Marineland filters come in various sizes and types for almost any size tank.
Food is also a top priority. It is very important to vary an Oscar’s food. This ensures that they will get all the nutrients that they require, although supplements may be needed as well. In their natural habitat, Oscar fish tend to eat a large amount of insects and crustaceans. They will also eat other fish as well. Anything they think they can fit in their mouths, they will try to eat. If you feed them only one type of food, such as feeder fish or beef heart, it can cause health problems in the fish that will not be visible until you wake up to find your fish belly up. Oscar are hardy fish but just like you, they need a balanced diet. If feeding feeder fish you will also need to be careful about introducing disease with the feeders. If the fish they eat is sick, the Oscar will probably end up sick as well. Limiting the amount of beef heart you feed your fish, if at all, is also recommended. It is higher in saturated fats that can cause liver problems in the fish if they eat too much of it.