Another compatible species for your Oscar aquarium, the silver dollar (Mylossoma pluriventre) is a peaceful, schooling fish that can be kept in groups of three to six with most other community tank species of similar size. They can grow to 6″ and probably larger. They live for several years.
The Silver Dollar is extremely sensitive to even the smallest quantity of nitrite before your nitrite kid can detect it they will start gasping for air, perform immediately a 30% water change and clean or replace your filters. Do not use aquarium salt to treat diseases in your tank as Silver Dollars do not tolerate salt well. They do best in soft moderately acidic water. Avoid using malachite green, as they can die of copper poisoning.
Silver Dollars are relatives of the Piranha but instead of being carnivores, they are mainly herbivores that require a diet high in vegetable matter, including any of the commercial Spirulina- and vegetable-based frozen, freeze-dried and flake foods. They will also accept small live foods, such as brine shrimp, bloodworms and glass worms. Supplement with parboiled peas, zucchini and romaine lettuce.
Silver Dollars love subdued lighting so provide them with floating plants which they may nibble on and adequate hiding places in the form of rocks, flowerpots and driftwood. The female will lay eggs among the floating plants. The eggs will immediately drop to the bottom, but will not be eaten. The eggs hatch after three days and the fry will become free-swimming within a week, attaching themselves to the tank glass where they will eat small plankton.