Silver Dollar
Metynnis argenteus
Also known as: Silver dollar tetra
Quick Facts
- Adult size: 14-15 cm (5.5-6 inches)
- Minimum tank size: 250 litres (66 gallons)
- Lifespan: 8–12 years
- Temperament: peaceful
- Swimming level: middle
- Diet: herbivore
- Minimum group size: 5
- Difficulty: intermediate
Water Parameters
- Temperature: 24–28°C
- pH: 5.5–7.5
- Hardness (GH): 36–214 ppm (2–12 dGH)
Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.
Care Summary
A coin-bright, deep-bodied schooling fish, like a giant peaceful piranha relative without the teeth or the temperament, the silver dollar brings the shimmer of a tetra shoal to the large-tank scale. A group cruising a big aquarium catches the light beautifully and behaves impeccably toward tankmates, which makes silver dollars an underused choice for a peaceful community of larger fish. Two things define their keeping: they need numbers and space (a nervous lone silver dollar in a small tank is a sad, jumpy thing), and they are committed herbivores that will eat almost any live plant, so a silver dollar tank is typically an open or hardscape-only one. Hardy and long-lived once settled, they are an excellent, characterful centrepiece for a roomy community that does not depend on live planting.
Tankmates
A large, peaceful, intensely schooling fish that must be kept in a group of at least five, ideally more, or it becomes nervous, skittish, and prone to crashing into the glass and decor when startled. Despite its size it is entirely peaceful toward other fish and will not eat tankmates, making it a good large community fish, but it is a dedicated herbivore that treats live plants as a salad bar and will strip a planted tank, so pair it with tough plants or none. Suitable companions are calm, similarly-sized fish: angelfish, larger gouramis, peaceful catfish, clown loaches, and other big community species. Avoid aggressive or fin-nipping tankmates, which exploit its timid nature. A tight lid helps, as startled silver dollars jump.
Compatible with
- Angelfish
- Pearl Gourami
- Bristlenose Pleco
- Clown Loach
- Denison Barb
- Congo Tetra
- Bala Shark
- Firemouth Cichlid
- Pictus Catfish
- Kissing Gourami
- Red Rainbowfish
- Severum
- Striped Raphael Catfish
Avoid keeping with
- Betta
- Oscar
- Large Cichlids
- Tiger Barb
- Fin Nippers
Common Problems
- skittishness and glass-crashing in groups smaller than 5
- eating live plants
- jumping from open tanks
- stress from aggressive or nippy tankmates
Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20