Silver dollar
Metynnis argenteus
intermediate careOverview
The silver dollar (Metynnis argenteus) is a large, disc-shaped, silvery shoaling fish — a peaceful, plant-eating relative of the piranha that brings a shimmering wall of movement to a big aquarium. Active and gregarious, it needs the security of a group and plenty of open water. Given the right space it is a hardy, long-lived and impressive fish, but it is easy to underestimate the tank size and shoal it truly requires.
Tank & water
A shoal of five needs a large tank of at least 250 litres (65 gallons) with a big footprint for swimming. Hold 24–28 °C with a strong filter and good flow on soft to neutral, well-cycled water.
- Open swimming space: these active fish need length and volume, not clutter.
- Tough or artificial plants only: they eat soft live plants — plan the aquascape accordingly.
- Secure lid: startled silver dollars can jump.
Feeding
As herbivores, silver dollars need a plant-heavy diet. Feed spirulina flakes and pellets, algae wafers and plenty of blanched vegetables (courgette, spinach, peas), with occasional protein such as frozen bloodworm. See our best fish food picks and the fish food hub. A well-fed shoal is less likely to demolish your plants, though it rarely leaves them entirely alone.
Tankmates
Peaceful and shoaling, silver dollars suit spacious communities with other large, calm fish — bigger rainbowfish, peaceful cichlids such as the severum, larger catfish and robust tetras. They shoal only with their own kind, so always keep five or more. Avoid small fish that may be intimidated and aggressive tankmates.
Frequently asked questions
The silver dollar is a peaceful, plant-munching shoaler that rewards a big tank with a dazzling display of coordinated movement. Give it space, a group of five or more, and a vegetable-rich diet, and it thrives for a decade.
Silver dollar — frequently asked questions
Do silver dollars need a big tank?
Yes. They reach 13–15 cm, are active swimmers, and must be kept in shoals of five or more, so a tank of at least 250 litres is needed. In too small a tank they become nervous and prone to crashing into the glass. Space and a group are non-negotiable for this fish.
Will silver dollars eat my plants?
Almost certainly. Silver dollars are dedicated herbivores that treat live plants as food and will strip a planted tank quickly. Keep them with tough plants like anubias and java fern, artificial plants, or a hardscape aquascape, and feed plenty of vegetables to satisfy their appetite.
Are silver dollars peaceful?
Yes — they are peaceful, if skittish, shoaling fish that suit a large community. Their nervous nature settles greatly when they are kept in a proper group of five or more, which gives them the confidence to swim in the open rather than dashing for cover.
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