Silver Dollar Fish All You Need To Know: Size, Types and More

The Silver Dollar Fish is a popular freshwater aquarium fish.

They are best known for their shiny silver appearance, peaceful temperament, and great tank mate compatibility.

Silver Dollars are also fairly low maintenance and can thrive in tanks as small as 20 gallons.

If you are interested in keeping the Silver Dollar then you are in the right place.

In this article we cover what to feed them, how big they get, tank mates and much more…

Silver Dollar Fish

Silver Dollar Fish 101

Metynnis argenteus

Silver Dollar Fish can be found in all sorts of shallow tributaries across the northern parts of South America.

They belong to the Characidae family and these stunning silver fish have adapted to live in areas with thick, dense vegetation which explains why they look flat and thin, like a silver dollar coin! Their bodies allow them to swim between long plants and stems as they occupy the upper water layer.

Although there are currently 11 recognized Silver Dollar species, the Metynnis argenteus is the most popular species. This article will focus on the Metynnis argenteus; however, they all have similar care requirements and dietary needs.

These shiny fish are quite common in the aquarium hobby and are kept in many tanks all over the world.

Their popularity is because of their peaceful temperament, attractive appearance, and high tank mate compatibility.

You can expect a healthy Silver Dollar to live up to ten years. This will depend on how well they are looked after and their genetic composition.

The only difficulty you should expect is in decorating the tank. This is because they are notorious for eating plants. This behavior has rewarded them with the nickname Plant Piranhas!

Expect to pay $7-$20 per fish.

Key Facts:

  • Experience Required: Intermediate.
  • Nicknames: Silver Dollars, Plant Piranhas.
  • Color Forms: Silver.
  • Size: 6 inches.
  • Tank Size: Minimum 20+ gallon.
  • Tank Temperature: 75°F to 82°F.

  • Hardy and tolerant
  • Peaceful temperament
  • Great tank mate compatibility
  • Very easy to breed

  • Have to be kept in groups
  • Can jump out of an aquarium
  • Will eat most aquarium plants

Silver Dollar Fish Appearance

A Silver Dollar Fish

Silver Dollars get their name because of their appearance.

They are rather flat fish but tend to be quite tall which makes them look slightly circular from the side. Their disk-shaped bodies help them to navigate their way through long-stemmed plants in the wild. They also have very sharp teeth.

Expect them to have an all-silver translucent body with hints of color dotted around.

These dots of color are often indicators that they are in a healthy environment. Males will also have patches of red on their anal fin which get darker during courtship, making it much easier to tell the genders apart. Their shimmery silver scales sparkle and shine all through the tank.

Some individuals will also have dark patches scattered around their body. Females tend to be the opposite and have less color variation.

Their fins are a triangle shape, but they also have forked caudal fins. Their heads are also somewhat triangular shaped and they have relatively lumpy bodies. If you pay close attention, they look like piranhas. This makes sense since they are from the same family.

Silver Dollar Fish can grow up to 6 inches long.

Types of Silver Dollar Fish

There are quite a few varieties of the Silver Dollar Fish including:

  • Red Hook Silver Dollar (Myloplus rubripinnis): This species is very easy to distinguish as they have a red anal fin which is outlined with black. They can grow up to 9 inches in aquariums making them one of the largest Silver Dollar species out there.
  • Spotted Silver Dollar (Metynnis lippincottianus): This type of Silver Dollar has black spots dotted around their body and can reach up to 6.5 inches. They look gray rather than silver.
  • Tiger Silver Dollar (Metynnis fasciatus) These fish also originate from Brazil and have a very distinctive striped pattern. The vertical stripes are bold and dark and stand out against a bluish silver body.
  • Black-Barred Silver Dollar (Myleus schomburgkii): Originating from the northern parts of South America, this species is also known as the disk tetra. These Silver Dollars are slightly smaller growing up to a maximum of 4.5 inches.
  • Silver Dollar (Metynnis hypsauchen): This is another species that people tend to use the name Silver dollar interchangeably with Metynnis argenteus. They look quite similar but this species tends to be a grayer tone.

Tank Mates

School Of Silver Dollars

Silver Dollar Fish are an incredibly peaceful species.

This means there is a wide list of compatible tank mates that will complement them quite nicely. Their schooling nature means that they mostly prefer each other’s company and are unlikely to bother specimens of different species in the tank.

Some of the best tank mates are peaceful bottom feeders such as the Bristlenose Pleco, Kuhli Loach, and Cory Catfish. These types of fish can coexist nicely as they will spend most of their time at the bottom of the tank away from the more adventurous Silver Dollar.

The best tank mates are:

  • Kuhli Loach
  • Cory Catfish
  • Clown Plecos
  • Bristlenose Plecos
  • Red Empress
  • Blue Dolphin
  • Bala Shark
  • Angel Fish
  • Blue Ram Cichlid
  • Green Terror Cichlid
  • Giant Danio
  • Pacus
  • Redtail Shark
  • Giant Gourami
  • Black Ghost Knife
  • Clown Loach

Although Silver Dollars are quite big, they are not aggressive. Any other large and peaceful species will get along just fine with them.

Non-compatible tank mates include Guppies, Tetras, and small Gouramis.

Another example of a non-compatible tank mate is Goldfish, which prefer colder waters, so also won’t be a suitable match.

Silver Dollar fish have also been known to prey on Brine Shrimp and small snails in the wild, so it is advised that snails and shrimp are not kept in the same tank. The likelihood of them eating these small invertebrates is quite low as they mainly prefer eating plants and other algae-based foods, but better safe than sorry!

Keeping Silver Dollar Fish Together

In the wild these fish tend to stay in small schools of around five.

You should always keep them in groups in an aquarium.

Keeping them in groups allows them to feel safe and protected. This also increases their quality of life as they are less likely to be stressed out. These fish are not known to display territorial behavior, but they may sometimes display slightly aggressive behavior especially during the breeding season.

Silver Dollar Fish Care Sheet

Full Size Silver Dollar Fish

Silver Dollars are quite hardy but this does not mean that they cannot get sick.

Ich disease or white spot disease, is a common physical illness that can affect most fish. It manifests as white spots on the body and fins. Other symptoms include rubbing against the tank or loss of appetite. Any unusual behaviors should be investigated to check if your fish have Ich disease.

Treatment for this disease is relatively easy as you can find medications for Ich at almost any aquarium store. By simply following the instructions on the medicine packaging, the disease can easily be cured. Additionally, you can add aquarium salt which further disinfects the tank.

Increasing the water temperatures will interfere with the bacteria causing this infection and kill them off.

Water changes should also be performed regularly to remove the buildup of potentially harmful bacteria. It is recommended that a minimum of 25% of the tank water should be replaced every two weeks.

To minimize the risk of Ich disease it is also important to make sure that your Silver Dollars have a balanced diet. Silver dollar fish are omnivores so it is essential that they are eating similar amounts of protein and plant-based foods.

Diets with little variation won’t contain all the essential nutrients that healthy Silver Dollars require.


In the wild Silver Dollars will primarily eat the vegetation that surrounds them.

However, they are actually omnivores.

Although they prefer plants they will also eat small shrimp and snails.

It is important that these ornamental fish have a diet that is fairly rich in proteins and lipids as this will maximize growth and help maintain their shiny appearance.

Because they are not bottom feeders they are unlikely to eat sunken foods. You can feed them anything from algae wafers and vegetable flakes to tasty protein-rich brine shrimp.

Letting them eat the plants in your aquarium is a huge advantage. They can keep plant growth in check and also prevent the overgrowth of algae.

Variety is key for their diet.

Whilst feeding fish dried and processed food is not a huge issue in general, you should make sure that these are not the only foods that your Silver Dollars eat.

You should watch closely when you feed them.

Larger and more active species can snatch away any food before the Silver Dollars have time to eat it. On their own, Silver Dollars are timid so won’t confront others if this occurs which could lead to malnutrition. Using feeding rings can combat this issue.

They should be given enough food that they can finish within 3 minutes or less and they should be fed twice a day.

What Food Can They Eat?

Processed Foods: Algae wafers and vegetable flakes are great options.

Plant Based: Lettuce, carrots, spinach, cress, cucumber, peas, and spring greens. Using these vegetables is a good way to make sure that their diet is vitamin-packed. They also like fruit and cooked vegetables such as potatoes and squash.

Protein Based: Mosquito larvae, brine shrimp, and bloodworms should be fed occasionally as a treat.


Silver Dollar Fish are schooling fish and will shoal in groups of at least 5.

They occupy the higher regions of the tank and are top dwellers. Because of this they can jump out of tanks so a hood is a must.

You will notice that they like to chase each other. This is a simple method of communication and solely an act of entertainment. They do this to develop stronger social bonds.

When kept alone they will hide away rather than freely swim around the tank.

These peaceful fish do not display any aggression so they are the perfect addition for community tanks. The only exception to this is during the breeding season, but other than that, they are unlikely to cause harm to other species.

Habitat and Aquarium Set Up

Silver Dollar Fish Swimming

Silver Dollar Fish tend to inhabit shallow river tributaries in South America.

These tributaries have long, thick vegetation.

They like to spend their time in darker regions of the river near various rocks and other debris, and in areas rich in driftwood and stones. Driftwood is particularly useful as it gives them an opportunity to hide from predators.

There will also be lots of peat and weeds which makes the water softer and acidic creating blackwater environments. Tannins in the water also contribute to low visibility.

In order to recreate the conditions of their natural habitat you should maintain moderately acidic water (pH 5-7) with a medium flow.

Silver Dollar Fish are quite hardy, though. So long as the water is clean, well-aerated and relatively clear they will be satisfied.

As for water parameters:

  • Temperature: 75-82°F
  • pH: 5.0-7.0
  • Water Hardness: 4-18 dGH

You will need at least a hang-on-back filter to keep the water clean.

They prefer clear waters as they tend to dwell in the upper parts of the tank, but the lighting should not be too bright as they also like to spend time among plants due to their largely herbivorous diet and they need shadowy regions to hide in when stressed or needing to relax.

Lighting should be very dim and subdued at around 1 watt per gallon.

Speaking of plants it is important to make sure you use very sturdy plants as they tend to nibble on almost any vegetation that they come across. Some plant species that work well are Java Moss and Hornwort.

It is also important to include rocks and driftwood. Dark gravel is the ideal substrate as it resembles the riverbed in their natural habitat.

Tank Parameter Requirement
Minimum Tank Size 20 Gallons
Tank Type Freshwater planted
Temperature 75-82°F
pH 5.0-7.0
Hardness 4-18 dGH
Flow Medium
Substrate Dark Gravel

What Size Aquarium Do They Need?

A single Silver Dollar Fish will need at least a 20 gallon aquarium.

However, because these fish need to be in groups you will need a 75 gallon tank for a minimum group of 5 fish. Any more than this will require an extra 10-15 gallons per individual.

History and First Sighting

The Silver Dollar Fish was first discovered by Ernst Ahl back in 1923 in South America.

There are estimated to be around 15 species of the Silver Dollar Fish, but there is a lot of controversy surrounding their taxonomy. For instance, Ahl described 18 species whereas fairly modern work had led to a reduction to 11 species:

  • Metynnis argenteus
  • Metynnis eigenmanni
  • Metynnis guaporensis
  • Metynnis hypsauchen
  • Metynnis lippincottianus
  • Metynnis dungermi
  • Metynnis maculatus
  • Metynnis mola
  • Metynnis orinocensis
  • Metynnis otuquensis
  • Myloplus rubripinnis

The most recently discovered species is the Neon Green Silver Dollar that is found in the upper Rio Nanay in Peru. This species has a green iridescent body which fades slightly as they get older. Males will still develop the typical red patches on the anal and caudal fins.

Not much is known about how or when this fish was first introduced into aquariums.

Like many other ornamental fish, the Silver Dollar Fish is likely to have been introduced to aquariums during the 1990s. Since then they have become a well-loved schooling fish.

They currently face no threat of endangerment or extinction mainly because they are rarely caught in the wild. The fact that the females can lay up to 2000 eggs means that they can quickly repopulate in the wild.

Breeding Silver Dollar Fish

Breeding Silver Dollar Fish

Breeding these fish is fairly easy as they will naturally spawn often.

Silver Dollars are naturally group spawners so you can raise them to a mature age (often one year) from when they are juveniles just for breeding. You can then transfer breeding pairs into a separate breeding tank.

To breed them you will need a breeding tank.

Within the breeding tank you should raise the water temperature and pH to the higher end of their range. You should also have dim lighting, a gentle water flow, and lots of plants.

In the wild they will spawn in flooded rivers with heavy vegetation so adding lots of floating plants will replicate these conditions. Plants also provide a safe space for the eggs to be deposited by the female. Java Moss works well here.

Their spawning period can be quite long.

Studies have been done to look at using Ovaprim to help speed up the spawning process.

To prepare the males and females for breeding you will need to feed them a protein-rich and plant-based diet. Males will show when they are ready to breed as the red patches on their fins will get darker.

Females can produce and lay up to 2000 eggs which will then be fertilized by the male. The eggs will look transparent with a slight hint of yellow.

The eggs will take around 3 days to hatch and the fry tend to eat their yolk sacs and become free-swimming after six to nine days.

You should feed the fry infusoria.

As they grow they can then eat crushed vegetable flakes, small plankton, and brine shrimp.

Only once they are mature can you start feeding them a proper adult diet.

Should You Keep The Silver Dollar Fish? (Summary)

Silver Dollar Fish
Other Common Names: Silver Dollar, Plant Piranhas
Scientific Name: Metynnis argenteus
Family Name: Charicidae
Distribution: South America
Size: 6 inches
Color: Silver
Care Level: Intermediate
Temperament: Peaceful
Lifespan: 10 years
Minimum Tank Size: 20 gallons
Tank Mate Compatibility: Very compatible

Silver Dollar Fish are certainly one of the most beautiful aquarium fish around.

They will spend their time in a shoal and develop very close bonds.

These top dwellers are ideal for community tanks as they are sociable and not likely to cause trouble in the tank. They work well with bottom feeders and even slightly aggressive species like cichlids.

They are also easy to breed, will eat a range of foods, and there are so many species to choose from!

Silver dollar for your thoughts? Let us know your questions in the comments section below…