|Scientific Name||Metynnis argenteus|
|Common Name||Silver Dollar|
|Adult Size||5 inches (14 cm)|
|Social||Peaceful, suitable for community tanks|
|Tank Level||Mid dweller|
|Minimum Tank Size||20 gallons|
|Diet||Herbivore, eats plants|
|pH||5.0 - 7.0|
|Hardness||up to 15 dGH|
|Temperature||75-82 F (24-28 C)|
Looking at the round, flat, and shimmery Silver Dollar, it is easy to see how it acquired the name. Although many specimens seen in shops are scarcely larger than the size of a dime, don't be fooled. Adults become much larger than their namesake, growing to nearly a half foot across.
There are well over a dozen species of Silver Dollars, all of which are similar in appearance. Metynnis argenteus, Metynnis hypsauchen, Metynnis lippincottianus, Myleus rubripinnis and Mylossoma aureum are all species regularly seen for sale in the aquarium industry.
Metynnis argenteus is the most commonly seen species for sale, and it can sometimes be distinguished from other species by small dots on their sides. Males have a longer anal fin that is tinged with red on the front. They are a schooling fish by nature and do best when kept in schools of three or more.
Silver dollars prefer subdued lighting, dark substrate, plenty of room to move about, as well as some good hiding places. Ideally, keep them in a school, which means a large tank. It’s advisable to use plastic plants or very sturdy live plants because they will eat live plants. They do best in soft moderately acidic water, although they're not fussy about water conditions.
Interestingly, Silver Dollars are in the same family as Piranhas, but instead of being carnivores, they are almost exclusively vegetarian. Their favored foods include vegetable flakes such as spirulina, lettuce, watercress, and cooked romaine or spinach. They will also eat cooked vegetables such as peas and squash. When feeding any fresh food, take extra care to remove any uneaten portions promptly, as it will foul the water.
Even though the Silver Dollar prefers a vegetarian diet, they will eat meaty foods as treats. They are especially fond of bloodworms, mosquito larvae (glass worms), and brine shrimp. If the Silver Dollars are in a community tank, watch them at feeding time to ensure that more active and aggressive fish don’t get all the food. Silver Dollars can be rather timid in a crowd and can end up underfed as a result.
Much like Angelfish, the best way to acquire a breeding pair is to purchase a half dozen juvenile silver dollars and raise them together. Although the parents will not consume the eggs or fry, other fish will, so when spawning, place them in a separate tank. To facilitate spawning, make sure the water is soft (8 dgH or below) and warm (80 to 82 F), keep the lighting dim, and provide fine-leafed plants (which will be eaten if they are live rather than plastic plants).
Eventually, a pair will spawn and the female will lay up to 2000 eggs. The eggs will fall to the bottom of the tank where they will hatch in three days. After approximately a week, the fry will be free swimming and able to eat fine foods such as commercially prepared fry food, finely crushed spirulina, or freshly hatched brine shrimp.