Silver Dollar Fish

Family: Characidae Silver Dollar Fish, Metynnis argenteusMetynnis argenteusPhoto © Animal-World: Courtesy David Brough
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I have 3 Silver dollars...they are full grown as I have had them for almost 7 years. One of them is huge and the other two are only about 4 inches long. I assume... (more)  Zebo

The Silver Dollar is one of the most readily recognized fish in the hobby, and a favorite too!

The Silver Dollar Fish Metynnis argenteus looks just as its name implies, round and 'covered with silver. These fish are characins called "Silver Dollar" because their body shape is almost round and is very compressed laterally. Their scientific name says it all, with the genus term Metynnis meaning "with plowshare" and the species name argenteus meaning "covered with silver".

The M. argenteus characins are generally a silver color, but with slight green and blue tints in the right light. There are also hints of red, especially on the anal fin of the male, which is edged in red. In some habitats they will have small dots on their sides.

This species and its close relative Metynnis hypsauchen, also known as the Silver Dollar, are virtually identical in both looks and aquarium care. Both these species are commonly available to the aquarist. They can be only be distinguished by a black blotch or shoulder patch found slightly above and behind each eye on the M. hypsauchen.

There are a number of fish known by the common name Silver Dollar. Most of them are members of the Metynnis genus which contains 14 described species and the Myloplus genus with only 2 described species. However M. argenteus along with M. hypsauchen are the two species generally referred to simply by this common name. Most of the other species have other qualifiers to their names, like the frequently encountered Red Hook Silver Dollar Myloplus rubripinnis, and others like the Striped Silver Dollar M. fasciatus (and sometimes M. guaporensis), the Spotted Silver Dollar M. lippincottianus, Red-spot silver dollar M. luna, Speckled Silver Dollar M. maculatus, Black-barred Silver Dollar M. otuquensis, and so on.

The peaceful Silver Dollar is a choice fish for many aquarists who want a community aquarium with good sized inhabitants. The Silver Dollar, though very peaceful, gets rather large and needs a good sized aquarium. They are a lively fish and like to hang out in schools, so get several if you can.

These fish are happiest in a large shallow aquarium with peat filtered water, dark gravel, and lots of plants and hiding places. The Silver Dollar does like to eat plants. So get plants that are not so tasty like java fern and hornwort, or you can use plastic plants.

For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care

Geographic Distribution
Metynnis argenteus
Data provided by
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Characiformes
  • Family: Characidae
  • Genus: Metynnis
  • Species: argenteus
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Silver Dollar Fish - Quick Aquarium Care
  • Size of fish - inches: 5.9 inches (15.01 cm)
  • Minimum Tank Size: 75 gal (284 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Moderately hardy
  • Temperature: 75.0 to 82.0° F (23.9 to 27.8° C)
  • Aquarist Experience Level: Intermediate
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Habitat: Distribution / Background

The Silver Dollar Metynnis argenteus was described by Ahl in 1923. This species is not listed on the IUCN Red List. They are found in South America. There information about their occurrences vary. Atlas references say they are found in Guyana, the Amazon east of Rio Negro, to Paraguay. This may actually be the occurrence of its close relative Metynnis hypsauchen, also known as the Silver Dollar Fish, as other sources suggest M. argenteus is possibly endemic to the Tapajós River basin in Brazil. This species is a schooling fish, mostly inhabiting heavily grown smaller tributaries and feeding primarily on vegetable matter.  In nature they are normally a herbivore in the wild but will eat meat if an easy meal presents itself.

  • Scientific Name: Metynnis argenteus
  • Social Grouping: Groups
  • IUCN Red List: NE - Not Evaluated or not listed


The Silver Dollar is a very deep bodied fish with a round almost disk like shape that is very compressed laterally. They can get reach almost 6 inches (15 cm) in length and can live for 10 years or more in captivity. They are a silver color with slight green and blue tints in the right light. There are also hints of red, especially the anal fin of the male which is edged in red. In some habitats they will have small dots on their sides.

  • Size of fish - inches: 5.9 inches (15.01 cm)
  • Lifespan: 10 years - They have a lifespan of 10 years or longer in captivity.

Fish Keeping Difficulty

Silver Dollar Fish are fairly hardy and easy to care for. Although this fish is fairly durable the aquarist must be prepared to maintain a very large tank. They are suggested for a fish keeper with some experience as a school or 4 or more will require an aquarium of 75 gallons or larger.

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Intermediate

Foods and Feeding

Since they are herbivorous the Silver Dollar will generally eat mainly vegetable foodstuffs including a variety of plants, lettuce, cress, chickweed, and large vegetable flake. A good spirulina formula would be beneficial.  These fish like to get the occasional treat of bloodworms and brine shrimp. This tetra prefers to eat multiple times a day. Offer only what they can consume in 3 minutes or less with multiple feedings per day.

  • Diet Type: Herbivore
  • Flake Food: Yes
  • Tablet Pellet: Yes
  • Vegetable Food: All of Diet - Lettuce, Spinach, peas, carrots, cucumbers, fruits, and boiled potatoes make great treats.
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

The Silver Dollar is easy to care for provided the water is kept clean. Aquariums are closed systems and regardless on size all need some maintenance. Over time decomposing organic matter, nitrates, and phosphate build up and the water hardness increases due to evaporation. To combat these ever changing conditions water should be replaced on a regular basis, especially if the tank is densely stocked. At least 25 - 50% of the tank water should be replaced every other week.

  • Water Changes: Bi-weekly

Aquarium Setup

The Silver Dollar is a large fish that will occupy all parts of the aquarium and need spacious open areas for swimming. To keep a school or 4 individuals or more will require an aquarium of at least 75 gallons. Juveniles can be kept in a smaller tank, but they grow quickly when well fed and will soon need a much larger tank.

They are hardy and quite disease resistant, so can handle a variety of water conditions. They need clean water, so good filtration is important and a moderate water flow. A large canister filter will work best for this fish. Adding a couple power heads will give the tank great water movement and keep the oxygen level high. With larger Silver Dollars a glass heaters are not recommended. These fish are very active and can easily shatter the heater. Make sure to have a secure lid because these fish are jumpers when startled.

  • Minimum Tank Size: 75 gal (284 L)
  • Suitable for Nano Tank: No
  • Substrate Type: Any
  • Lighting Needs: Moderate - normal lighting
  • Temperature: 75.0 to 82.0° F (23.9 to 27.8° C)
  • Breeding Temperature: 80.5° F - Breeding temperatures are between 79 - 82° F (26 - 28° C).
  • Range ph: 5.5-7.5 - Breeding ph is between 6.0 - 7.0.
  • Hardness Range: 4 - 18 dGH - For breeding, hardness needs to be below 10° dGH.
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: Middle - These fish will swim all over but mainly in the middle of the aquarium.

Social Behaviors

The Silver Dollar is a peaceful fish and great in a large community tank with other large peaceful fish. Smaller community fish won't fare as well, as they will likely be eaten by large Silver Dollars. These fish are best in groups of 4 or more. Good tankmates include the larger peaceful catfish like plecostomus and the doradids.

  • Venomous: No
  • Temperament: Peaceful - Although this fish is peaceful it is best to have similar sized tankmates.
  • Compatible with:
    • Same species - conspecifics: Yes - They are most comfortable when kept in schools of 4 or more individuals.
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Threat
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Slow Swimmers & Eaters (): Monitor
    • Shrimps, Crabs, Snails: Safe - not aggressive
    • Plants: Threat

Sex: Sexual differences

The male has a longer anal fin which has a red tinge on the front of it.

Breeding / Reproduction

The Silver Dollar Fish are easy to spawn, they will do so in a school. Suggested water conditions: 79-82° F (26-28° C); pH 6.0-7.0; below 10° dGH. Place clumps of plants on the surface so they will spawn in between them. The female will lay up to 2000 eggs which will fall to the bottom and hatch after 3 days. The parents will not eat the eggs so there is no need to remove them. The fry will attach themselves to a surface and eat small plankton. See the general description of how to breed characin fish, see Breeding Freshwater Fish: Characins.

  • Ease of Breeding: Difficult - Breeding is not difficult, but it is only possible in a very large tank with precise water conditions.

Fish Diseases

The Silver Dollar is very hardy and disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won't have to deal with health problems or disease. Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance.

A good thing about the Silver Dollar is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your Flame Tetra the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. Stressed fish are more likely to acquire disease.

As with most fish they are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Silver Dollar Fish is readily available in pet stores and online, and is reasonably priced.


Author: David Brough CFS, Jeremy Roche
Lastest Animal Stories on Silver Dollar Fish

Zebo - 2015-02-08
I have 3 Silver dollars...they are full grown as I have had them for almost 7 years. One of them is huge and the other two are only about 4 inches long. I assume they are different varieties as they have never gotten bigger. I lost one of them when he ate the plastic plants and died from it, so I recommend no fake plants. If you feed them a supplement of algae tabs and romaine you can also put live plants in the tank. They will nibble on them, but that's what they just have to buy more plants once in a while.

Ray - 2014-10-04
I have a female silver dollar purchased September 1990. It is now 24 years old. The only documentation I have is family members who have seen it over the years. My wife and I are amazed that it is still alive and wonder how much longer it will live!

  • Clarice Brough - 2014-10-09
    Wow! That is awesome. They average 10 years or more, but you'll have to let us know what the 'or more' means, because you're breaking new ground:)
  • Theresa - 2015-01-15
    My mother inherited my two silver dollars which I originally purchased while living at home back in 1994 making them about 21 years old. They stayed after I moved out. They are still as energetic as ever--the only noticeable differnce is that they do have cataracts. She used to call them her 'teenagers', but I guess they have outgrown that phase.
david - 2014-12-06
Want to buy sliver dollar fish male and female.

Charles Damanis - 2010-01-20
I have 9 Silver Dollars in a 30 gal tank. I Love them because they out live all other fish you have. I think I have had them for about 5 years or so and they are about 4.5" long right now. Over the past five years they have had their share of viruses and sicknesses due to water quality as well as introducing "dirty" fish into the tank that may have had Ick and other problems.
It seems like I always have them on a medicinal regiment of Metafix, stressZyme, stressCoat and every now and then Erithromiacin anti-biotic powder form (also used in humans).

Here are my suggestions...Erithromiacin is good when your silver dollars have cloud eye and even tail and fin rot and redness in odd areas. It does not damage your water although you cant use a filter with it (I still keep my Ammo Chips in though). The down side is all the water changes you will have to do. Its annoying if you have a big tank, but why do you have a big tank if you can't stand up keep. My thoughts are to transfer some water from the regular tank and add treated water (not straight from the tap) into a smaller tank and transfer your silver dollars into the smaller tank to treat them in a sort of quarantine (just as long as you DO NOT have a parasite, if you do leave the fish where they are because you need to kill the parasite in the normal tank). If you have Ick I suggest Aquari-sol. It is a liquid solution that is better for fish with sensitive skin and it doesn't change your water green, make sure your doses are the right measurement, you do not want to poison your fish.
IMPORTANT: I put in some aquarium salt and raise the temp to about 79-80'F when treating fish with medicine. It is always good to have some salt in your tank. Just remember the only way to get rid of salt in your water is to do water changes so do not over salt your tank. Place some (depending the size of your tank) in after every 3-5 water changes.

DO NOT BUY PLANTS. The silver dollars will eat all of them no matter how much you feed them. Even plants suggested by this web page will not work with your silver dollars. Obviously if you have baby silver dollars they can not eat your plants as quick but they still will.
IMPORTANT: The lack of plants will mean that there is less Oxygen in the tank. I put in a long Air Stone and the silver dollars love to swim through it. Its fun watching them get used to it at first they are cautious then the pack leader will test his or her might and try to get through them. Eventually they all go through the bubbles. Im sure they like the way it tickles.

Romain lettuces is a must. Highly nutritious for you and your fish. It also makes your mind up when you're thinking about testing a new plant in the tank. Just put a piece of lettuce in the tank and a few hours later you will know not to get plants.
They love Shrimp pellets. They nearly choke on them because they shove the whole thing in their mouth and suck on them like cigars. You will NOT need to dump a considerable amount in order to get one into each ones mouth. I have 9 and usually dump 15. It's bad but I do not do it regularly. You can also just throw a few in while the lettuce is in as a treat only to those who grab them first. I use flakes but don't like to do so. Too many flakes gets you PLANARIA (flat worms). I have Planaria and it is impossible to get rid of them.
Important: They will eat/pick at small fish like tetras (when the silver dollars are larger). Only because they think that they are fish flakes. I also had a three inch butterfly fish that floats on the top of the tank. It also sleeps on the top and at night the silver dollars would swim up and bite it thinking it is food. It then died and they are all over it... All I found was a fin floating.

Useful information:
Too many decorations will not be good for your fish. They may like places to hide but if you place driftwood in your tank they are likely to run into it and hurt themselves. Sometimes this will lead you to believe that your fish are sick but it may just be that they ran into something. I have not tried this but have been thinking about it...I believe if you paint or tape an aquarium scene (the paper on the outside that has pictures of plants and whatnot) they will be less likely to crash into the glass. The glass fools them sometimes. They are not as smart as us and something to tell them stop may be useful.

Tank Size:
Bigger is better, they love to swim or just hang out but when they get bigger they start to get black stripes on their side. That means they're stressed and a bigger tank is needed. At this point you will have to battle sicknesses regularly because they are more susceptible to sickness when stressed out. I have 9 in a 30 gal but they deserve to be put in a 55 gal now. I also do not have any other fish in my tank.

I hope the information I have left is useful. This information has been learned the hard way through my experience with the fish. They are a joy to have and if they get any bigger I'm going to have to stop myself from getting my fishing pole.

  • Sheryl - 2010-04-20
    I have been blessed with a coworker wanting to give us his 55 gal established with silver dollars and tetras. We have not had any experience with silver dollars so this experience you had through trial and error I find most informative. Thank you so much!
  • Tom - 2014-02-08
    Your silver dollars get sick because you overcrowd them. 9 silver dollars in a 55 is over doing it, 30 is worse. I have noticed if they actually have room, and you do your regular water changes, they rarely if ever get sick.
david - 2014-12-06
Want to buy sliver dollar fish male and female.