If I asked you to pick your favorite shoaling fish, what species would it be? For me, it is undoubtedly the simple but stunning Silver Dollar (Metynnis Argenteus)
A distant cousin of the piranha and pacu, the Silver Dollar (metynnis Argenteus) has been a favorite amongst fish keepers for many years, especially in the US. However, they are underrated by some people, classified as boring and plain!
With this Silver Dollar complete care guide, we hope to change that opinion and show you that the Silver Dollar is a fish worthy of keeping. We are going to make you fall in love!
Silver Dollar Characteristics and Care
There are several different species of the Silver Dollar with the Metynnis Argenteus being the most well known and archetypal. They are named for their resemblance to a silver dollar, an old American coin, with argenteus meaning ‘covered in silver’. It is an incredibly apt description since the Silver Dollar appears to shine.
Unfortunately, the Silver Dollar can often find itself looking for a new home as many people purchase them without realizing how big they can and do grow. Adult Silver Dollars commonly achieve a size similar to that of a saucer! They also need to be kept in large groups for them to thrive and be happy in the home aquarium.
The following is a rough guide to the care requirements of the Silver Dollar:
|Scientific Name||Metynnis argenteus|
|Tank Size||30 Gallons Plus|
|Water Conditions||73-78° F, KH 4-8, pH 5.0-7.5|
Color and Appearance of the Silver Dollar fish
The Silver Dollar is a rounded, almost diamond shaped flat species that is covered in tiny scales and has a small mouth with enlarged lips. They are brilliant silver in color that almost seems to shimmer. In the right light, they may also appear to have slight green or blue tints.
The male of the Silver Dollar species is smaller than the female but has a longer anal fin that can have a small tinge of red on it. The male also has a dark or black outline on the edge of the tail fin. This makes them fairly easy to sex should you be considering breeding. During mating courtship, the male also develops two dark blemishes above their gills.
Silver Dollar are generally purchased at a size of around 5 to 6 centimeters but will grow up to around 6 inches (15 cm) in length and diameter. They are one of the larger species of freshwater fish and appear stunning when kept in a group.
I know that you are probably now thinking that the Silver Dollar does not sound very exciting to look at! You couldn’t, however, be more wrong. In a beautifully set up aquarium with upwards of six of them shoaling together, they are gorgeous and quite something to look at.
The habitat of the Silver Dollar fish
The Silver Dollar is believed to have originated from the Tapajos river basin in Brazil. This river at 12,000 miles long, runs right through the Amazon forest and is a major tributary to the
Amazon river. It is one of the largest clear water rivers and accounts for approximately 6% of the volume of water in the Amazon river.
Preferring weedy side arms of the Amazon river, the Silver Dollar fish can be found in large schools throughout the thickly planted tributaries. This is partly due to their preference for slow-moving waters and partially due to these areas providing good cover. Silver Dollar are preyed upon by birds, larger fish, and reptiles.
In their natural habitat, the Silver Dollar diet is mainly made up of vegetarian matter although they do also enjoy feeding upon worms and small insects.
Silver Dollar Diet
We have already covered what the Silver Dollar will eat in their natural habitat but what will they need in the home aquarium?
Well, as a mainly herbivorous species they will eat pretty much anything plant-based they are offered. This includes flake, pellet, cucumber, courgette (zucchini), lettuce, squash, peas, and string beans.
Beware, however, they will also eat anything plant-based that they shouldn’t as well! This means, all those lovely plants you are caring for in their home aquarium are in danger of being devoured and destroyed. Fake plants are usually the way to go with this species.
As well as plants, Silver Dollar love to eat insects, bloodworm, and brine shrimp. They will eat these live, frozen, and freeze-dried. In fact, they will eat almost anything they are offered and voraciously.
Silver Dollar are known to be aggressive eaters that will fight amongst themselves over an algae wafer! They will require feeding several times a day.
The behavior of the Silver Dollar in an aquarium
Although the Silver Dollar can be food aggressive on occasion, they are otherwise a generally peaceful species that spend the majority of their time shoaling together. Why they shoal is not exactly known, but it certainly works for them regarding predation. Silver Dollar when feeling preyed upon will work together to intimidate their attacker.
Best kept in larger groups Silver Dollar can be skittish if startled. This is especially true the smaller the group they are kept in. When frightened Silver Dollars will dart around the aquarium quickly, which can lead to them injuring themselves.
Although easily startled by human presence Silver Dollar are not timid around tank mates. They are, in general, good companions of other fish. They can, however, be aggressive to smaller species as they may have a slight bullying instinct. Some have been known to even eat smaller fish, but this behavior is rare.
An active fish that is capable of speedy swimming the Silver Dollar will mainly be found mid-level in an aquarium and in their shoal. They do, however, sometimes break off in ones or twos to search for food or mischief! As stated before Silver Dollars are voracious plant eaters that can destroy your carefully grown plants in days.
Although Silver Dollar is a shoaling fish that spend most of their time together, you may see occasional disputes. These tend to be between males in the group and are usually associated with grappling for dominance rather than territory. The most common time for this behavior is close to breeding.
The majority of the time, Silver Dollar make for a soothing, harmonious aquarium watching experience. They are the kind of fish you want to watch after a long, hard day at work. That is not to say, however, that they are boring. If you fancy a little excitement going on in your Silver Dollar aquarium just drop in an algae wafer and wait. You will soon see them chasing each other around the place in an attempt to be the one to eat!
Caring for Silver Dollars
The first consideration regarding the care of the Silver Dollar should be whether you can house them correctly. They need an aquarium of at least 55 gallons but preferably much bigger. They also prefer aquariums that are shallow but lengthy with peat filtered water and dark colored gravel. Since they can live for up to ten years, you need to be pretty sure you can care for them for this length of time.
A fairly hardy species, the Silver Dollar can tolerate slight water parameter fluctuations and imperfections. This does not mean, however, you can neglect the maintenance of your aquarium. Ideal water parameters for the Silver Dollar are a pH of 6 to 7.5, 8 to 15 dH, and a temperature of 75 to 85℉ or 24 to 28℃. Water conditions can be measured using a Freshwater Aquarium Test Kit available from Amazon.
Tank décor-wise, Silver Dollar need places to hide in order to feel safe. Lots of plants, fake if you don’t want live ones destroyed, are ideal. Live plants, if they are your choice, that may be suitable for Silver Dollar aquariums include species such as java fern and hornwort. This is because it is believed that Silver Dollar don’t like the taste of them.
Another decor you could consider is terracotta pot, driftwood, rocks, and such. Please note, however, that anything you do include in the Silver Dollar aquarium should not have sharp edges in case they bump into them during a fright and flight. On a similar note Silver Dollar aquariums should not be placed in busy areas of the house or anywhere they are likely to get knocked. This is due again to them being naturally skittish on being frightened, which you want to avoid.
Subdued lighting is perfect for the Silver Dollar, they do not appear to like anything too bright. You may also want to ensure that you have a tight-fitting lid that cannot be lifted easily as Silver Dollars have been known to jump when startled.
Choosing your Silver Dollar is not a difficult process, you just need to ensure they appear healthy. As you are going to be buying a group of six or more, the recommended amount, you do
not need to worry about whether you are picking males or females as the chances are you will have both. Silver Dollar are usually offered for sale at around 5 to 6 centimeters in size.
Please note the Silver Dollar should not be kept in small numbers as they are more inclined to be skittish in smaller numbers. A minimum of six is recommended with more being better than less. Silver Dollars are not hard to acquire as they are available in most pet and aquatic stores.
Once home you will need to acclimate your Silver Dollar before releasing them into the aquarium. Although they are fairly hardy and can adapt to water changes, the temperature can be a problem. Silver Dollar do not react well to sudden water temperature change, meaning that when performing maintenance, water added to the aquarium needs to be as close to the internal temperature as possible.
Common illnesses Silver Dollar may be susceptible to include constipation and ich (a disease which is characterized by small, white nodules on the fins, skin, and eyes, caused by Ichthyophthirius multifiliis, an ectoparasite). You can treat ich with a simple aquarium salt solution and by increasing the temperature slightly. Constipation is best avoided and can be relieved by simply feeding your Silver Dollar a varied diet. Should your Silver Dollar suffer from constipation feeding them daphnia may help.
If your fish becomes ill or starts to show unusual behaviors then read our complete guide to diagnosing and treating many of the common diseases in our complete guide.
When it comes to handling your Silver Dollars, you will need to use a large net to capture them. Capturing should not be necessary, however, as they do not need removing during water changes and maintenance. Fingers and hands are completely safe around these herbivores, food and plants are not. You could consider treating your Silver Dollar every now and then to a sacrificial plant! Think of it like a fish treat to be given occasionally.
Overall, the Silver Dollar is probably one of the easiest species to keep. This is in part due to their being one of the hardier species, and partly due to being, more often than not, laid back and peaceful. They do, however, require a rather large aquarium making them seem like they need a more experienced aquarist. This is not at all true and novices should not be put off. After all, without going into the scientific reasoning, the larger the aquarium, the easier they are to look after. The Silver Dollar, in my opinion, is an excellent ‘beginner’ fish!’
Breeding and Sexual Differences
If you are planning to breed Silver Dollar Fish you will need at least one mating pair. The best odds of achieving this lie in purchasing a juvenile shoal and raising them together. This way you are virtually assured of buying both sexes.
You can, however, easily sex Silver Dollar Fish – as they age, the females tend to be larger, whilst the males have longer anal fins with possible tinges of red on them. Males also usually have a dark or black outline around their tail fin.
Silver Dollars are not difficult to breed and it can be done in their aquarium or in a breeding tank. If you plan on breeding in a different aquarium however, you will need to ensure that it has lots of hiding places and preferably broad-leafed plants. These are the preferred laying place for Silver Dollar releasing eggs.
Actual mating behavior is easy to spot with Silver Dollar as the males will chase the female around. Males also usually develop two black smudges behind their gills when they are interested in a female. The chasing itself will only stop when the female finally allows the male to swim beside her. The male will then wrap his body against the female until she releases her eggs.
Once the eggs have been released, the male will fertilize them and it will take three to four days for them to hatch. The fry will immediately begin to swim around the aquarium and should be fed spirulina flakes and crushed brine shrimp. Not feeding the fry plenty of food may result in them becoming stunted. We like Hikari First Bite fry food available from Amazon. If you’ve not seen or tried it, then take a look at the reviews. It’s a very popular fry food around the world especially in Japan and Singapore.
Unlike other species, the Silver Dollar will not eat their young so in a species-only aquarium, if well fed, most fry will survive. However, if your Silver Dollar have tank mates that do eat fry you will need to take precautions. This may be that you use a breeding tank or that you separate the fry once hatched.
Tank mates perfect for Silver Dollar Fish
There are a plethora of species of fish that are suitable tank mates for the relatively easy going Silver Dollar. Medium to large American cichlids, for example, are ideal. Severums, Green terrors, and Oscars are all reported to do well.
Bottom feeders are another good option especially if you wish to have activity on all levels of your aquarium. Corydoras, yoyo loaches, and clown loaches are good examples here. Bala sharks and plecostomus are also often housed with Silver Dollar but remember that aquarium size could be a limiter here.
Smaller fish such as guppies, tetras, etcetera can also do really well with Silver Dollar since they are in general peaceful. They also make a really stunning visual with the large Silver Dollar dwarfing the smaller. Be aware though that not all Silver Dollar will play nicely with smaller fish, some may even eat them!
It is worth noting here that the Silver Dollar can make for an absolutely wonderful species-only aquarium too. They do not necessarily need the company of other species to be enjoyed. Bear in mind also that Silver Dollar need a large aquarium when kept on their own. To keep other species additionally, you will need an aquarium of at least 6 foot long or more!
The Silver Dollar is absolute proof that simpler looking fish can be just as attractive as their multicolored, fancy friends. They are astoundingly beautiful to look at and can make a great centerpiece to any aquarium.
They are also a fun fish to watch so long as you refrain from startling them. This is especially true when you encourage their feisty side out with the offering of a nibble or two. If you fancy a little more laid back observation? Then just leave them to do their own thing and enjoy!
Either way, you wish to view your Silver Dollar, they are a fish that I would highly recommend keeping. They are easy to care for, easy to keep happy, and a real delight.