The Definitive Guide To Silver Dollar Fish

If you are a fish keeper with a bit of experience and are looking to expand your fish collection, Silver Dollar Fish might be the fish for you.

They are peaceful medium-size fish, ideal for community aquariums.

These silvery colored fish get their name from how they look. Laterally flattened, they look exactly like an old silver dollar.

If you are looking for top water schooling fish, they are one of the best choices. Keep reading to learn how to successfully care for them, breed them and much more…

Category Rating
Care Level: Intermediate
Temperament: Peaceful
Color Form: Silver
Lifespan: 10 years
Size: 6 inches
Diet: Omnivores
Family: Characidae
Minimum Tank Size: 75 gallons
Tank Set-Up: Freshwater
Compatibility: Large peaceful fish

Overview

Metynnis argenteus
Silver Dollar Fish (Metynnis argenteus)

Silver Dollar Fish, Metynnis argenteus, get their name from the way they look. They are large silvery fish from the South American rivers.

They belong to the Characidae family, the same family as Piranha and Pacus. However in contrast to their more aggressive relatives, they are peaceful herbivorous fish, perfect for large size community aquariums.

Silver Dollar is a common name given to a number of different species in the Metynnis genus.

Their scientific name describes the fish perfectly. Metynnis, meaning ‘with plowshare’ which refers to the laterally flattened body, and, argenteus, meaning ‘covered with silver’.

They are quite hardy fish and with good care can live for around 10 years.

You can easily find them in pet shops and online for modest price. As they are best kept in groups, they are usually sold in bulk.

Typical Behavior

They are large peaceful schooling fish that need plenty of swimming space. You should keep them in a group of at least 5 individuals. They can be quite skittish and reclusive if kept alone.

Interestingly, they are are pelagic fish, which means they will spend most of their time swimming close to the water surface. They get startled easily and will jump out of the tank.

Whilst they are peaceful fish, during eating time they can be aggressive and chase each other around the tank.

Silver Dollar Appearance

Silver Dollar Fish Appearance
Silver Dollar Fish (Metynnis hypsauchen)

As the name suggests, they look like an old silver dollar. They have a round body which is laterally flattened.

Silver Dollar Fish is a generic term which refers to multiple characin species. Metynnis hypsauchen and Metynnis argenteus are two popular species and they look very similar.

The only way to spot the difference between these species is the black patches found behind the eyes and on the body on M. hypsauchen.

Another common species found in the aquarium trade is the Red Hook Silver Dollar (Myleus rubripinnis). They can be identified by their different coloration and fin shapes.

Spotted Silver Dollar Fish

As the name gives away, the Spotted Silver Dollar Fish is identified by the silvery ground color and the black dots on its body. They are found in Brazil and French Guyana, and can reach up to 6.5 inches.

Red Hook Silver Dollar Fish

This fish has a distinctive black-trimmed, red anal fin. Its coloration is much more obvious than other Silver Dollar fish.

They can reach 22 inches in the wild and up to 9 inches in aquariums.

Red Hook Silver Dollar Fish

Habitat And Tank Conditions

Silver Dollar Fish originate in South America.

The waters here are dark and filled with peat. They will also have gravel and rocks with dense vegetation and lots of hiding spots. The rivers that they live in are often full of debris such as driftwood, large rocks and weeds.

As far as currents, water flow here will be moderate.

Silver Dollar Fish Tank Setup

Silver Dollars are tropical freshwater fish – the tank should mimic their natural environment as much as possible.

They will mainly swim in the middle and top part of the water column and therefore need open areas for swimming.

These fish are quite hardy and have some tolerance toward different water conditions. They require clean and well oxygenated waters with a good filtration system and moderate flow. A couple of power heads can be used to help out with water movement and oxygenation.

However, make sure not to use glass power heads as your Silver Dollars will be very active and could easily shatter the power head.

They are jumpy fish, preferring dim lighting and a dark background. We suggest using dark colored gravel as a substrate. You need a lot of open space but also some hiding places around the back and sides of the tank (you can build these with large rocks and driftwood).

As they are herbivores, you should only keep plants that are not very tasty; try java fern and hornwort. The alternative is to use artificial plants.

The temperature of the water should be kept between 75-82°F with a pH of 5.5-7.5. You have a flexible water hardness between 4-18 dGH.

What Size Aquarium Do They Need?

Silver Dollars need at least a 75 gallon. This is the minimum tank size for a school of 5 individuals.

Allow 10 gallons of water for each additional fish you add.

Silver Dollar Fish Tank Mates

Silver Dollar Tank Mates

Silver Dollar Fish are large peaceful and active fish.

These fish are great community fish that swim in the top part of the aquarium. If you want to add some contrast, you can look for other large peaceful fish such as catfish that spend most of their time near the tank bed. Plecos and Doradids could be a good fish to start with.

Further ideal tank mates are peaceful South and Central American Cichlids such as freshwater Angelfish, Firemouth and Green Terror Cichlids. Giant Danios, Pacus and Anostomus are also good tank companions.

We do not advise to keep your Silver Dollars with smaller fish such as Gouramis, Bettas and Tetras as they might get eaten.

Shrimps and snails can be a good addition; however they too might get eaten.

Keeping Silver Dollar Fish Together

Silver Dollars are at their best when kept together. They are schooling fish, so they feel safer and more protected in a group.

You should aim to keep them in a group of at least 5 individuals.

What To Feed Them?

Silver Dollars are actually omnivorous fish; however, they prefer an herbivorous diet. In nature they usually feed on the surrounding vegetation including terrestrial plants.

You can feed them a variety of plants such as lettuce, cress, chickweed, cucumber, peas and spring greens. You can also feed them seaweed such as spirulina along with large vegetable flakes.

Spinach, carrots and fruit can also be used as an alternative food source.

They will appreciate random treats such as bloodworms, brine shrimp and boiled potatoes.

Herbivorous fish play an important role around the globe in all major environments. Both freshwater and seawater herbivore fish help to control community structures of certain habitats.

By feeding on the surrounding vegetation, they prevent algae or coral to overgrow and steal all the nutrients from the surrounding waters. They help to keep a healthy and stable environment by grazing on the surrounding plants.

You should feed your Silver Dollars twice a day, offering only enough food that can be consumed in 3 minutes or less at each feeding.

Silver Dollar Fish Care Guide

Silver Dollar Fish

Silver Dollars are pretty hardy fish.

As aquariums are closed systems, harmful substances such as nitrate, phosphorous and decomposing organic matter will build up over time.

This is why water should be replaced on a regular basis and at least 25-50% of the water should be replaced every other week.

Even though Silver Dollars are quite resilient fish there is no guarantee that your fish will not catch a disease or an infection. Remember that every time you add something new to your tank, it is a potential source of infection.

A clean water tank, a balanced diet and an environment that most resemble the natural habitats will help your fish to settle making it a healthy happy fish.

One of the most common diseases in ornamental fish is an ectoparasite known as Ichthyophthirius multifiliis – more commonly known as white spot disease or Ich. Your fish will start to develop white spots on its gills, fins or scales.

This protozoan life cycle depends greatly on water temperature. Higher water temperatures above 77°F will interfere with the different life stages and will help prevent an outbreak.

How To Breed

Silver Dollar Fish Swimming

Silver Dollars are relatively easy to spawn in captivity providing they have a large comfortable environment. In the wild, you will find them spawning in shallow waters and in heavily planted areas of flooded rivers.

You will first need a mated pair.

For the best success of finding breeding pairs always keep them in a group, raising them from juveniles to maturity. This fish usually reaches maturity around 1 year of age (about 4 inches in length).

If you have a pair, you should separate them from the rest of the school. You can also precondition males and females to spawn by feeding high quality plants and vegetables. When the males are ready to spawn, their color will darken especially around the anal, caudal and dorsal fins.

For a successful spawn, you should get a separate shallow tank of at least 40 gallons with soft warm waters. Keep temperatures around 79-82°F, pH at 6.0-7.0 with water hardness of 4-8 dGH.

You can provide a gentle water flow by using an air-powered sponge filter.

Dim light, soft spots of java moss and floating plants on the surface will help during breeding. Males will start chasing females around the tank. When the females are ready to spawn, they will release the eggs near or on the floating plant and the male will fertilize them.

The female can produce up to 2000 eggs, transparent and slightly yellow. These will sink to the floor.

It is easier to raise the fry without the parents however Silver Dollars don’t generally eat their young. The eggs will hatch in about 3 days and the fry will be free-swimming after 6-9 days.

You can feed infusoria-type foods to the fry until they can eat larger things such as small plankton, brine shrimp nauplii and vegetable flakes. Fry will reach adult size in about 6-8 months.

Are Silver Dollar Fish Suitable For Your Aquarium? (Summary)

Silver Dollars are hardy tropical freshwater fish. They are large peaceful schooling fish that make the perfect addition if you want a community aquarium with good sized fish.

If kept alone they can be quite skittish and are best if kept together.

Their name, Silver Dollars, is quite a generic name to refer to different Metynnis species, different in colors and sizes.

They are best for aquarists with some previously experience. They will eat anything that you give them, however, they prefer plants and vegetables.

A Silver Dollar for your thoughts? Leave a comment in the section below…

Robert Woods Portrait
Robert Woods is the creator of FishKeeping World, a third generation fish keeper and a graduate in animal welfare and behavior. He is also a proud member of the Association of Zoos and Aquariums, the Marine Aquarium Societies of North America and the Nature Conservancy.

6 Comments

    • Hi Bev, given the size difference between Silver Dollars and Guppies, I would say no. Although Silver Dollars prefer a herbivorous diet, they are actually omnivores so if they’re feeling peckish they might eat them. Thanks, Robert

  1. I have 5 loony size little ones and I also have a pinky size arowana. My tank is 8’x2’x2’. I’ve seen in videos they get along in a tank but arowanas aren’t the gentle kind. Should I be concerned?

    • Hi Christina, they should be fine, just keep an eye on the size of them to ensure they don’t get eaten. Many thanks, Robert

  2. Hello. We inherited our silver dollar from my MIL. He is ~17 years old. Yes, 17, as she had him when I met my husband in 2002. His tank mates back then were kissing fish. When we brought them home only the silver and one kissing fish remained. The kissing fish died about 8 years ago. I tried introducing other compatible smaller fish but our silver kills them. I’m a bad fish mom as I never researched them and didn’t know they do better in groups. He’s kept clean and happy. Seems quite healthy. I’m wondering if it’s too late to introduce 2 more silvers for companionship or has he been alone long? Thanks

    • Hi Shannon, it’s extremely difficult to answer this question as it’s not something I’ve ever come across. I’m going to leave your question here in case anyone with a similar experience can share their thoughts with you. Thanks, Robert

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