Profile of the Silver Dollar Fish Species

Schreitmuller's silver dollar (Metynnis hypsauchen), side view

It is simple to see how this fish got its name by taking a look at the rounded, flat, and glistening silver dollar. Don't be deceived, even if many specimens seen in stores aren't much bigger than a glossy penny in size. Adults can reach about a half foot across, making them significantly bigger than their namesake.

Species Overview

COMMON NAMES: Silver dollar

SCIENTIFIC NAME: Metynnis argenteus

ADULT SIZE: 6 inches (16 cm)



Family Serrasalmidae
Origin Brazil, Guyana
Social Peaceful, suitable for community tanks
Tank Level Mid dweller
Minimum Tank Size 20 gallons
Diet Herbivore, eats plants
Breeding Egglayer
Care Intermediate
pH 5.0 to 7.0
Hardness Up to 15 dGH
Temperature 75 to 82 F (24 to 28 C)

Origin and Distribution

Although the Tapajós River Basin in Brazil is where Metynnis argenteus is native, it is found widely in shallower tributaries and river systems throughout northern South America. It is only one of the dozen various species referred to as "silver dollars" in the aquarium trade. Species including Myleus rubripinnis, Mylossoma aureum, Metynnis argenteus, Metynnis hypsauchen, Metynnis lippincottianus, and others are frequently offered for sale in the aquarium trade.

Metynnis argenteus, which is typically regarded as the model silver dollar, is frequently mistaken for Metynnis hypsauchen due to their similar look. The little spots on the sides of Metynnis argenteus can occasionally be used to differentiate it from other species.

Colors and Markings

Silver dollars made by Metynnis argenteus are typically sparkling all over, but certain lighting might give them a subtle green or blue hue. They will have little colored spots on their flanks in healthy settings. Crimson hints may also be seen, notably on the male's anal fin, which has a red edge.


Since silver dollars are naturally schooling fish, it is better to keep them in groups of six or more. They are a relatively calm shoaling species that struggles to survive on its own, but even a big group will become cautious and wary if left without cover.

They are strong enough to handle the company of much larger species while still being calm enough to be trusted with fish that are considerably smaller than themselves. Many non-aggressive cichlids and peaceful big catfish like plecos and doradids would be ideal choices.

Silver Dollar Habitat and Care

Silver dollars are resilient and simple to maintain. Despite this fish's relative toughness, the aquarist needs have a relatively sizable tank for them. A 75-gallon aquarium or bigger is needed for a school of six or more. Silver dollars like quiet surroundings, a dark surface, lots of space to move about, and lots of suitable hiding spots.

Because they will consume the majority of live plants, it is best to use plastic plants or really robust live plants. Although they are not picky about water quality, they thrive in soft, somewhat acidic water. Silver dollars don't have high standards for water quality, but they do best in clear, circulating water that has been carefully filtered, aerated, and purified.

Silver Dollar Diet and Feeding

It's interesting to note that although silver dollars and piranhas both belong to the same family, the latter are virtually entirely carnivorous. Their favorite meals are leafy greens like lettuce, watercress, and cooked romaine or spinach, as well as like spirulina. Additionally, they will consume prepared veggies like peas and squash. Any uneaten food should be removed as soon as possible after giving any fresh food, since its decomposition will contaminate the water.

The silver dollar will occasionally consume meat, despite preferring a vegetarian lifestyle. They particularly enjoy brine shrimp, mosquito larvae (glass worms), and bloodworms. In a communal tank, keep an eye on the silver dollars at feeding time to make sure that more boisterous and aggressive fish don't take up most of the food. Some silver dollar people can be particularly shy with others, which can lead to them becoming hungry. Feeding rings will probably help to solve this problem.

Gender Differences

The anal fin of the male is longer and has a crimson tint on the front. The male will also grow two sizable black spots that are vertically aligned right beyond the base of the pectoral fins during courting and breeding. The male fins' crimson hue deepens and develops black edges. Additionally, some male specimens will have additional black marbling on their bodies. In the course of courting and reproduction, females seldom, if ever, display color variation.

Breeding the Silver Dollar

Breeding silver dollars is simple. They will occasionally reproduce on their own in a sizable, suitable aquarium. Start with a dozen or more youngsters, grow them to maturity together, and then breed them. When they are around a year old and about four inches long, they will be ready to reproduce. It is advisable to train the males and females in separate tanks before breeding to maximize breeding success. Feed them a high-quality plant and vegetable diet for seven to ten days, along with occasional meaty treats.

Although they may also breed in established couples, they naturally spawn in groups. Breeding pairs ought to be taken out of their group and into a breeding tank. Although the parents won't eat their own eggs or fry, other fish may, so keep them in a separate tank when spawning.

Make sure the water is soft (8 dgH or less) and warm to encourage spawning (80 to 82 F). Provide fine-leafed plants; they will be consumed if they are live rather than fake plants. Keep the illumination modest. The males will darken and their red hints will become more prominent as they are about to spawn, especially around the anal, caudal, and dorsal fins.

A couple will eventually give birth, and the female will lay up to 2,000 eggs. The eggs won't be troubled by their vegetarian parents since they will fall to the bottom of the tank, where they will hatch in three days. The fry will be able to eat fine foods like commercially prepared fry food, finely crushed spirulina, or recently hatched brine shrimp after about a week.

More Pet Fish Species and Further Research

If silver dollars appeal to you, and you are interested in some compatible fish for your aquarium, read up on:

Check out additional fish breed profiles for more information on other  fish.