Silver Dollar Fish: Species Characteristics and Care

With their round, flat, and shimmering appearance, it's easy to see how silver dollar fish got their name. While juveniles may resemble a dime, adults grow to nearly six inches in diameter.

Characteristics

Origin and Distribution

Metynnis argenteus originates in the Tapajós River Basin in Brazil but is widespread in shallower tributaries and river systems across northern South America. It is only one of a dozen different species known in the aquarium trade as the "silver dollar." Metynnis argenteus, Metynnis hypsauchen, Metynnis lippincottianus, Myleus rubripinnis, and Mylossoma aureum are all species regularly seen for sale in the aquarium industry.

Generally considered the archetypal silver dollar, Metynnis argenteus is often confused with Metynnis hypsauchen, which is similar in appearance. Metynnis argenteus can sometimes be distinguished from other species by their small dots on their sides.

Colors and Markings

Metynnis argenteus is typically shiny silver, occasionally exhibiting a green or blue tint. Healthy habitats reveal small tinted dots on their sides, with males displaying red edges on the anal fin.

Tankmates

Silver dollars naturally thrive in schools of six or more. Though peaceful, they become skittish without adequate shelter.

They coexist peacefully with smaller fish and can tolerate larger species. Suitable tankmates include peaceful large catfish like plecos and doradids, as well as many non-aggressive cichlids.

Silver Dollar Habitat and Care

Silver dollars are hardy and easy to care for. Although this fish is fairly durable, the aquarist must maintain a very large tank for them. A school or six or more will require an aquarium of 75 gallons or larger. Silver dollars prefer subdued lighting, dark substrate, plenty of room to move about, as well as many good hiding places.

It’s advisable to use plastic plants or very sturdy live plants because they will eat most live plants. Provide plants around the ends and back of the aquarium for the fish to hid in, but leave the center of the tank open for swimming. They do best in soft moderately acidic water, although they're not fussy about water conditions. Silver dollars are not overly demanding about water quality, though they do best in clean and clear, well-aerated, and well-filtered moving water.

Silver Dollar Diet and Feeding

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, and leafy greens such as 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 their decay will foul the water.

While preferring a vegetarian diet, they also enjoy occasional meaty treats like bloodworms and brine shrimp. During feeding, ensure they receive enough food, as more aggressive fish may dominate. Feeding rings can help mitigate underfeeding. The use of feeding rings will likely mitigate this issue.

Gender Differences

Male silver dollars have a longer anal fin with a red tinge. During breeding, males develop distinctive black spots and richer red fin coloration. They may display darker marbling on their bodies, whereas females remain less colorful and become rounder during the breeding season.

Breeding the Silver Dollar

Breeding silver dollars is straightforward, as they may spawn in a well-suited aquarium without assistance. Start with at least six juveniles, allowing them to mature together. For optimized breeding, condition males and females in separate tanks, feeding a high-quality plant and vegetable diet with occasional meat for 7–10 days.

Typically group spawners, silver dollars can also breed in pairs. Transfer breeding pairs to a separate tank to protect the eggs and fry from predation by other fish.

For spawning, ensure the water is soft (below 8 dGH) and warm (80–82°F), with dim lighting. Include fine-leafed plants in the tank, although live plants may be eaten.

A breeding pair will eventually lay up to 2,000 eggs, hatching in three days. Approximately a week later, fry become free-swimming and can consume fine foods like commercially prepared fry food, crushed spirulina, or newly hatched brine shrimp.

More Pet Fish Species and Further Research

If silver dollars appeal to you, and you are interested in some compatible fish for your aquarium, read up on:

• Bala shark species profile
• Blue gourami species profile
• Upside-down catfish species profile

Check out additional fish breed profiles for more information on other freshwater fish.