Freshwater Fish

Silver Dollar Fish – metynnis argenteus: Care Guide

The silver dollar fish is a popular and unique freshwater fish that has been a staple in tanks for quite some time.

They have a very interesting and attractive appearance, but that is not the only reason that makes them a great fish to own.

Silver dollar care is a fairly simple process that won’t take a lot of time or give you a lot of headaches. These fish require relatively little maintenance and will live a long time if you keep your end of the bargain.

They are also great for community tanks. The list of possible silver dollar fish tank mates is quite long!

In this guide, we cover everything you need to know about silver dollar fish and how to care for them. Then you can run out and get one for yourself!

Species Summary

Silver dollar fish (scientific name: metynnis argenteus) can be found throughout South America in rivers containing large amounts of long-growing vegetation. Their tall, slim build makes them perfect for navigating in this environment and swimming through stems with ease.

They feed mainly on plants and are known for their ability to devour any plant in their path. In fact, one of its nicknames is “piranha plant!” This is worth noting because it will affect how you decorate and fill your tank when it comes to plant life.

Silver dollar fish are also used to a variety of hiding places in their natural habitat in addition to plants. Rocks and driftwood are scattered throughout the water in which they live.

These are top-dwelling fish, meaning they will spend most of their time in the top half of your freshwater aquarium. Knowing this will come in handy for when you map out potential tank mates later on.

Life expectancy

The typical lifespan of a silver dollar fish is about ten years. However, it is not uncommon for them to exceed this limit in a year if they have good genetics and receive optimal care.

Due to their natural habitat, these are very hardy fish. However, this still means you can shorten its lifespan significantly if you don’t maintain proper tank and water conditions. As long as you take those things seriously, you should expect to see them live a pretty long and happy life!


The silver dollar fish looks like a silver dollar (shocking). Their bodies are tall and flat, giving them a rather circular appearance from the side.

Most of its body is quite shiny, but it becomes more translucent when you get to its fins. This further accentuates its similarities to the silver dollar.

Its dorsal fins somewhat resemble a slanted equilateral triangle beginning at the highest point on its body. The front edge of the dorsal fin is usually duller than the rest.

Its caudal fins are slightly forked and perfectly symmetrical. The silvery caudal peduncle of these fishes extends a little towards the caudal fin.

Silver dollar fish have slightly bulging bodies. Starting at his head, it’s a pretty neat triangle at the top and bottom to the midpoint. Then, where its dorsal fin begins, it angles downwards before striking a very light blow. Meanwhile, at the bottom, it flattens out before making a sharp turn toward the caudal fin.

Author’s Note: Silver dollar fish come from the same family as piranhas (characidae). When you compare their heads, you can definitely see the similarities.

Types of Silver Dollar Fish

There are a few types of silver dollar fish that you will see quite often. The standard silver color is by far the most popular, but they are not alone.

Red Hook Silver Dollar Fish

The red hook silver dollar fish has a very pronounced red anal fin that closely resembles a ship’s rudder. The rest of their bodies look very similar to the classic silver dollar, but the coloration can sometimes be a bit more patchy.

spotted silver dollar fish

The Spotted Silver Dollar is a neat variation that many aquarists seem to enjoy. They have a darker primary color on their body (more gray than anything else) and are covered in a series of dark brown spots.

tiger silver dollar fish

The tiger silver dollar fish is our personal favorite type. It is a very clean silvery blue with a series of large dark vertical stripes. This is a fun fish to watch swim by!


The average size of a silver dollar fish is around 6 inches long. There are occasional reports of them reaching 8 inches, but that’s not to be expected.

These are not small fish, which means you will need to plan your tank accordingly. They are not only long, but also tall! The only thing that saves space about silver dollar fish is their width.

Silver Dollar Fish Care

Silver dollar fish care is not rocket science. These are hardy, long-lived fish that can thrive in a wide range of conditions.

This gives you the luxury of not having to be paranoid about perfect tank conditions. That said, there are still a few things you’ll need to know.

tank size

A 75 gallon tank should suffice for your silver dollar fish. This assumes a minimum of 5 fish for your tank. These are training fish that do much better in a group than alone, so we do not recommend including less to save space.

You will want to have a long tank for your adult silver dollar because they are active fish that like to swim. This will give them some distance to cover without feeling tight.

Author’s Note: If you plan to exceed 5 silver dollar fish in a tank, add 10 to 15 gallons per additional fish.

water parameters

Maintaining the correct water parameters is crucial when it comes to silver dollar fish care. Despite their hardy nature, they can get into trouble if the parameters change too much.

  • Water temperature: 75°F to 82°F
  • pH levels: 5-7
  • Water Hardness: 4-18 dGH – More experienced aquarists prefer somewhere in the 8-15 range.

What to put in your tank

Silver dollar fish require a well-made habitat for their enrichment and comfort. These fish are prone to high levels of stress if they spend time in an environment that they do not understand or lack what they need.

First, you’ll want to include a decent amount of plants that they don’t find tasty. This will allow them to feel at home without you having to add new plants every other day. If these fish like the plants in their tank, they will gobble them up in a matter of days!

Two great options are java moss and hornwort. These will provide them with a familiar and comfortable environment, but they will not tempt the appetite.

A large amount of driftwood and rocks will also come in handy. Even though silver dollar fish spend most of their time in the top half of the tank, they will still appreciate having places to hide.

A gravel substrate is ideal as it will perfectly mimic riverbeds in their natural habitat. Dark gravel is preferable.

Author’s Note: It’s smart to use one or two powerheads to achieve the ideal water flow. This will help enrich the water with an adequate amount of oxygen so your silver dollar fish can thrive.

Possible common diseases

There is no species-specific disease you need to worry about when sticking to a silver dollar fish care plan. These fish are very durable and hardy which can make you breathe a little easier as an owner.

However, this does not mean that they cannot get sick. Silver dollar fish can get many of the same common diseases that other freshwater fish get if you don’t take care of them (such as ich).

The most effective way to avoid this is to take water quality, diet, and stress management very seriously. All of these play an important role in the health of your fish, and keeping them under control will significantly reduce the risk of them getting sick.

Food and Diet

The silver dollar diet can be a bit confusing at first. While these fish are technically omnivorous, they spend most of their time gobbling up plants.

You have many options when it comes to your preferred plant-based food source. Some of our favorites are:

  • seaweed wafers
  • plant-based flakes
  • cucumbers
  • Green peas
  • Lettuce
  • Other green leafy vegetables
  • Seaweed

They will also appreciate the occasional treat of bloodworms and brine shrimp, but these should be fed very infrequently.

The standard feeding schedule for silver dollar fish is very convenient. These fish can do well on a twice-daily schedule, which is much more convenient than the 3-4 daily feeding sessions that other species require.

behavior and temperament

The silver dollar fish is a very nice fish to keep. They are calm, non-aggressive and quite active.

You will hardly ever see them display any kind of aggression towards each other or other fish in your tank. This makes them a great community fish that you don’t have to worry about.

Since they are feeding fish, you will always see them swimming with their friends. It is rare to see one wandering around on their own, as that will make them very shy and nervous.

These fish will spend most of their time in the top half of your tank. This can be an excellent mix with other species that spend their time in the middle or bottom of tanks.

Author’s Note: Since the silver dollar is a top-dwelling creature, you’ll want to make sure you have a sturdy tank hood. They are known to jump!

Silver Dollar Fish Tank Compatibility and Mates

There are many critters that make excellent tank mates for silver dollar fish due to their gentle nature. For the most part, these fish just want to go about their business and find plants to nibble on!

Peaceful bottom feeding fish are usually quite compatible with silver dollars as they spend most of their time in the top half of the tank. This means that not only will both species not want to fight, but they won’t even be near each other in the first place!

Some of our favorites in this category are clown and bristlenose plecos. Kuhli loaches and cory catfish also make good silver dollar tank mates.

There are several cichlids that also make great tank mates. Oscar fish, red empress, and blue dolphin are strong cichlid pairings.

Due to their size and durability, you have many options when it comes to finding a tank mate for silver dollar fish. Just because you don’t see it on our list above doesn’t mean it’s not compatible! If they have similar water requirements and are not aggressive, they can probably work!

Author’s Note: Fish that are super small may not work as silver dollar fish tankmates. Silver dollars are big and might be mistaken for a snack! This means betta fish and neon tetras are not an option.


Breeding silver dollar fish is fairly straightforward once you have identified a compatible mating pair.

You will need a breeding tank that is somewhere in the 40 to 50 gallon range. Water temperature and pH levels should be at the higher end of their normal range to stimulate the process.

Floating plants are also a necessary inclusion in the breeder tank. This will mimic their natural environment and make the fish think they are in an acceptable place to spawn.

The eggs the female creates will fall to the substrate and the parents won’t be very involved with them after that point. This may seem a bit strange as these are fish that prefer to be close to the surface of the water, but it has worked for them so far!

After a few days the eggs will hatch and you will need to feed them food such as plankton and small flakes to help their growth.

tie it all together

The silver dollar fish is one of our favorite freshwater fish. They are unique, fun to watch, peaceful and very low maintenance!

Taking care of them is a fun experience that anyone can handle once they know what to do (which this guide has dealt with). Also, due to their long lifespan, you will likely have these fish for quite some time as long as you provide them with a healthy tank to live in.

If you have any additional questions about silver dollar care that we didn’t cover in this guide, please let us know. We want to make sure these resources are as helpful as possible!

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