Silver dollar
Metynnis argenteus
A large, disc-shaped silver fish related to piranhas but plant-eating; skittish, shoaling and able to strip a planted tank bare.
Key facts
- Body length
- 5.9 in without fins
- Minimum tank
- 81 gallons
- Group
- 5+
- Temperament
- Peaceful, shy
- Care level
- 3 / 5
- Lifespan
- Not well documented
- Diet
- Spirulina flakes, vegetables, herbivore pellets
- Origin
- Rio Tapajós basin, Brazil
- Hardier than22%
- Bigger than73%
- Calmer than68%
Water: their range vs yours
Silver dollar tank mates
- AngelfishGets along in shared water.Good mates
- Blue dolphin cichlidGets along in shared water.Good mates
- Bristlenose plecoGets along in shared water.Good mates
- Chinese algae eaterGets along in shared water.Good mates
- Clown loachGets along in shared water.Good mates
- Common plecoGets along in shared water.Good mates
- Firemouth cichlidGets along in shared water.Good mates
- Golden mbunaGets along in shared water.Good mates
- Leopard sailfin plecoGets along in shared water.Good mates
- Peacock cichlidGets along in shared water.Good mates
- Pearl gouramiGets along in shared water.Good mates
- Rosy barbGets along in shared water.Good mates
- BettaSilver dollar can eat young or small Betta; adults are big enough to be safe.Risky
- Blood parrot cichlidSilver dollar outcompetes the slow-eating Blood parrot cichlid for food; target-feed to make sure it eats.Risky
- Bronze corySilver dollar can eat young or small Bronze cory; adults are big enough to be safe.Risky
- Convict cichlidConvict cichlid (aggressive) will bully the peaceful Silver dollar.Risky
- DemasoniSilver dollar can eat young or small Demasoni; adults are big enough to be safe.Risky
- DiscusSilver dollar outcompetes the slow-eating Discus for food; target-feed to make sure it eats.Risky
- Neon tetraSilver dollar can eat Neon tetra: prey body depth 0.7 cm ≤ mouth 3.8 cm.Avoid
- Harlequin rasboraSilver dollar can eat Harlequin rasbora: prey body depth 1.1 cm ≤ mouth 3.8 cm.Avoid
- Fancy guppySilver dollar can eat Fancy guppy: prey body depth 0.8 cm ≤ mouth 3.8 cm.Avoid
- Panda corydorasSilver dollar can eat Panda corydoras: prey body depth 2.4 cm ≤ mouth 3.8 cm.Avoid
- OtocinclusSilver dollar can eat Otocinclus: prey body depth 0.7 cm ≤ mouth 3.8 cm.Avoid
- Cherry shrimpSilver dollar can eat Cherry shrimp: prey body depth 0.8 cm ≤ mouth 3.8 cm.Avoid
How we check
The numbers the tank model uses for silver dollars: water as ideal and tolerated ranges, bioload from adult mass, space, flow and how they act on other species.
- Standard length
- 15 cm (SL)
- Adult mass
- 250.61 g
- Bioload at 25 °C
- 34.79 BU
- Min. water
- 260 L net
- Min. footprint
- 180 × 38 cm per group
- Group
- 5+ (best 5)
- Swims in
- middle, top
- Flow
- moderate
- Body / fins
- compressed disc, normal fins
- Diet type
- herbivore
- Fin nipper
- none
- Sensitive to
- —
Sources: Seriously Fish: Metynnis argenteus · FishBase: Metynnis argenteus
Care notes
Silver dollars come from densely vegetated tributaries of the Rio Tapajós, and several Metynnis species are sold under the same name. They are nervous fish that feel safer in a shoal with dim light and cover.
Keep five or more in a tank around 75 gallons with a 6-foot footprint and a lid. They eat even tough plants, so use artificial ones or hardy replacements, and make vegetable foods the base of the diet.
Questions
What size tank does a silver dollar need?
At least 81 gallons (260 litres of water after decor). Adults reach about 5.9 inches without fins.
How many silver dollars should be kept together?
Keep at least 5, ideally 5 or more: fewer feel exposed and hide or turn nippy.
What water do silver dollars need?
75–82 °F, pH 6–7 and 0–10 dGH. Silver dollars come from Rio Tapajós basin, Brazil.
How long do silver dollars live?
Not well documented with good care.
What fish can live with silver dollars?
Good tank mates include Angelfish, Blue dolphin cichlid, Bristlenose pleco, Chinese algae eater and Clown loach. Each is checked both ways for size, fin nipping, temperament, territory and shared water.