Hot Water Fish

Silver Dollar Fish

  • Scientific name: Metynnis argenteus, Metynnis anisurus
  • Common Name: Silver Dollar, Silver Dollar
  • Aquarium size: 250 liters
  • Temperament: Calm
  • Temperature:  Between 24º and 28º
  • pH: Between 6 and 7
  • Diet: Vegetarian
  • Length: 14 cms


The silver dollar fish, also known as silver dollar, is a fish of the genus Metynnis, of the characid family , therefore it is a fish for hot and fresh water aquariums.
Its name is due to its flattened shape and silver color, quite similar to the coin for which it is nicknamed.
They are distant cousins ​​of piranhas, with whom they share a family, although these fish are vegetarians, so hard-leaved plants should be incorporated into the aquarium, if we do not want to run out of vegetation.


They are fish that in the aquarium can measure up to 14 centimeters. Its shape is rounded, semi-discoidal and bright silver when it is directly exposed to light.
It appears that the males are somewhat larger than the females. It is not the only sexual dimorphism, in males the anterior part of the anal fin is colored red, in addition to being a little more elongated than in the female.
They have an adipose fin, and all the fins are transparent, except the anal one in the male.
They have small eyes in relation to their body, and like piranhas, their mouth is provided with good teeth with very sharp teeth.

Distribution and habitat

This species comes from the northern regions of South America, although according to some publications, it seems to be limited to the Tapajós River in Brazil.
It can be found on the banks of the river, where the vegetation is more abundant and where it finds food easily.

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Aquarium conditions

The silver dollar fish needs a good size aquarium, between 200 and 250 liters would be the right thing to do, diffused light, dark peat soil and good oxygenation of the water.
Ideally, the aquarium contains good vegetation, the problem is that they are great plant eaters, so they must be plants with hard leaves, somewhat bitter, which we will surely have to replace regularly.
An alternative is to include plastic plants.
The water temperature should be between 24º and 28ºC, with a pH between 6 and 7. Soft water.


They are vegetarian fish , consume any type of plant food. We can feed it zucchini, cucumber, peas, and all kinds of green leafy vegetables. We can complement this diet with dry preparations based on algae, specific for fish.

Behavior and compatibility

It is a peaceful and gregarious fish that needs to live with more of its species. It is recommended to have at least five to six specimens, so that they swim together.
A community aquarium should include fish of similar size or larger, as they could eat other smaller fish.
Since they usually swim in the upper and middle part, a good idea is to include fish that occupy the rest of the aquarium, such as catfish , that will occupy the bottom part.

Fish compatible with the Silver Dollar

Compatible fish without restrictions

  • Corydora
  • Scalars, Angelfish
  • Snail Apple
  • Betta 
  • Rainbow
  • Guppy
  • Molly
  • Ancistrus
  • Tiger Barbel
  • Gourami Pearl

Compatible fish without restrictions

  • Botia Clown
  • Ramirezi
  • Zebra fish
  • Kribensis
  • Platy
  • Little nun
  • Ax fish

Restricted Compatible Fish

  • Paradise Fish
  • Discus fish
  • Barbel Cherry
  • Otocinclus
  • Drunk
  • Wasp Fish
  • Killis
  • Neon tetra
  • Guppy endler
  • Rasbora Galaxy


Metynnis argenteus is not as easy to reproduce as other characins, but it is not impossible, as long as a series of recommendations are followed:

  • To be successful in breeding the silver dollar, we must use a breeding tank.
  • The aquarium should have a temperature of 28ºC, and be somewhat more acidic than usual.
  • To aid spawning, a good idea is to change the water, but make it warmer than the aquarium.
  • The male will be ready to spawn, when they acquire a darker coloration, especially we can see it in its anal, caudal and dorsal fin.
  • At the moment of courtship, the males chase the females.
  • When the female releases her eggs (up to 2,000 eggs), they are fertilized by the males.
  • Although they are not fish that usually eat their eggs, once fertilized it is a good idea to remove the adult fish.
  • The fry will appear three days after the eggs are fertilized.
  • They should be fed with specific preparations, until they reach a size, in which they begin to tolerate other foods.

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The Metynnis argeteus, is a fish quite similar to the Metynnis hypsauchen, the two specimens can be sold under the denomination silver dollar or silver dollar, although they are actually two different species.
They are so similar that they are easy to mistake, although the Metynnis hypsauchen has a black spot above and behind the eyes.
There would not be too much problem in the cares, because they would be exactly the same for both species.

Photos of the Silver Dollar fish

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