Adult silver dollars are peaceful, schooling freshwater fish that typically grow to between 15 and 20 cm (6–8 inches) in diameter. Despite their relation to piranhas, they are primarily herbivores and require a large, open swimming area of at least 200–300 litres for a school of five or more.
Species & Physical Traits
While often sold under the generic name "silver dollar," several distinct species exist in the aquarium trade, each with slight variations in adult size and appearance:
Common Silver Dollar (Metynnis argenteus): The standard variety, reaching roughly 15 cm (6 inches) with a uniform shimmering silver body.
Striped Silver Dollar (Metynnis hypsauchen): Very similar to the common variety but often displays faint vertical striping and reaches 15–18 cm.
Red Hook Silver Dollar (Myleus rubripinnis): Notable for its larger adult size, potentially reaching 20–25 cm (8–10 inches), and a prominent red-edged anal fin.
Spotted Silver Dollar (Metynnis lippincottianus): Features a silver body covered in dark spots and grows to approximately 15 cm.
Blackberry Silver Dollar (Myleus schomburgkii): Recognized by a large black blotch on its flank, reaching about 15 cm.
Adult Care & Tank Requirements
As active, fast-swimming adults, these fish need specific conditions to thrive:
Tank Dimensions: According to Fishlore, while 200 litres is the minimum, a 6-foot long tank is preferred for adults because of their tendency to "zoom" and dart when spooked.
Vegetarian Diet: Unlike their predatory relatives, adults require a diet heavy in plant matter. Expert sources recommend spirulina flakes, lettuce, watercress, and cooked peas.
Plant-Safe Aquascaping: Adults will shred and eat most live plants. It is recommended to use plastic or silk plants, or very hardy live species like Java Fern and Anubias.
Water Parameters: They prefer soft, slightly acidic water (pH 6.0–7.5) with temperatures between 24°C and 28°C.
SKU: RBM
