The Silver Dollar fish comes from South America and has been a favorite among tropical fish hobbyists for many years. They get to be about 15cm or about the size of a saucer. They are a brilliant silver in colour and in some varieties, the male will have a small amount of red on its anal fin. They do best in schools of 6 or more and can become scared easily if not in a school. However, even in small schools they can still be very skittish, especially if you approach the tank too quickly. If you come up too fast or if you make quick movements they may start darting around the tank and could possibly injure themselves. For this reason, make sure that there are no sharp tank decorations in the aquarium.
They are mostly peaceful but can be extremely aggressive eaters. Watching them eat can be fun. Drop an algae wafer into your tank and watch the other Silver Dollars chase the one that gets it around the tank. For the plant keepers out there, they are herbivores and notorious for the serious damage that they can do to your live plants. 
For food, they will accept most foods including vegetable flakes, pellets, frozen, freeze dried and live foods.
The Silver Dollar Fish can be fairly hardy once acclimated, but avoid fluctuating water parameters. When you are doing your water changes try to put in water that is as close to the same temperature as possible and don’t let the nitrates get too high!
Species – Metynnis argenteus
Common Name – Silver Dollar
Origin – South America
Diet – Herbivore
PH Range – Alkaline 6 – 7.5
Temperature – Tropical 24 – 28°c
Breed Type – Egg layer