Category: Tetra
Common Names: Silver Dollar, Silver Dollar Tetra
Scientific Name: Metynnis argenteus
Family: Characidae
Minimum Tank Size: 30 Gallons
Care Level: Easy
Temperament: Peaceful
Max Size: 6 Inches
Temperature: 72-80 F
pH: 6.0-7.5
Tank Level: Middle
Colors: Silver
Diet: Herbivore
Breeding: Easy
By AlejandroLinaresGarcia [CC BY-SA 4.0]Silver Dollar Tetra: Species Overview
Silver dollar tetras is a general name for several fish within the Characidae family that have a similar appearance. Fish in the Characidae family are closely related to the piranha. The silver dollar tetra has a round shape and bright silver color, making them an attractive choice for fish keepers wanting a schooling fish.
The tropical-loving silver dollar tetra was first discovered in 1923 by the German zoologist Ernst Ahls. Silver dollars are an excellent option for novice fish keeping, given that they have relatively lenient water parameters. We’ll share those details here so that you’ll be ready to bring home your fish by the time you finish this article.
Distinguishing Features
A silver dollar tetra gets its enigmatic name from its resemblance to a silver dollar coin (albeit one with fins!).
These fish have adorable, nearly perfectly round bodies. They’re silver in color with shiny and semi-translucent characteristics.
But in some cases, you may see hints of gold or light brown on the silver dollar tetra’s body. The red hook silver dollar variety also has a reddish-orange mark on its anal fin.
While we’re on the subject of different varieties of silver dollar tetras, it’s common to find pet stores selling several types of fish under the silver dollar name. They include:
- Red hook silver dollar
- Spotted silver dollar
- Tiger silver dollar
As their names imply, spotted silver dollar fish have (dark brown) spots on their body, and tiger silver dollar fish have dark vertical stripes.
But overall, the standard silver-colored tetra is the most popular choice for aquariums.
Silver dollar tetras have an opaque dorsal fin and a slightly forked caudal fin.
These fish have thicker heads compared to their thin bodies. If you’ve ever seen a piranha, this feature will make you understand why silver dollar tetras have a close relationship with their more notorious counterparts.
Origins
Silver dollar tetras originate in South America and have genes that closely resemble the fearsome piranha. But don’t worry—these tetras won’t bite you.
You’ll find them primarily populating Brazil’s Tapajós River basin. However, they also enjoy spending time in shallow freshwater tributaries and rivers in various tropical areas of South America.
Silver dollar tetras congregate in the topmost part of the water column in the wild. They school in groups as they dart between aquatic plants that float and grow up from the substrate.
It’s common for them to encounter driftwood and other debris in the water.
Between that, heavy rain that sometimes strikes the area where they live, and decaying plant matter, their natural substrate is dark and dense with organic material, sand, and pebbles.
Silver dollars strongly prefer clear water, which they happily explore between densely weedy areas once the weather settles.
Size
A silver dollar grows large for the tetra species, averaging around six inches long. Some fish keepers even say their silver dollars reached an impressive eight inches.
While it’s uncommon for silver dollar tetras to grow past a half foot, offering them lots of space and a high-quality diet can improve their chances of increased growth.
Silver dollar tetras are on the tall side, so you’ll need to keep this in mind when setting up their tank to ensure they have sufficient space to swim.
When it comes to differences between genders, females tend to have a slightly girthier appearance than males.
Lifespan
Silver dollar tetras have an incredibly long lifespan, averaging ten years. But with excellent care and good genetics, these fish can sometimes live even longer.
Domesticated silver tetras will rely on a well-maintained aquarium and a healthy diet, among other factors, to live a long life. Regardless, you can expect silver dollar tetras to outlive most tank mates in their aquarium.
Genders
You can tell male and female silver dollar tetras apart by observing their anal fin. Males develop a fin with a red edge, even when they don’t belong to the red hook variety.
Male silver dollar tetras have a longer anal fin than females, and they temporarily grow two black spots at the base of their pectoral fins when they’re getting ready to mate.
These males often develop deeper colors and some marbling with darker colors might even occur when they’re preparing to impress a female.
In contrast, females remain the same color regardless of their mating stage.
Female silver dollar tetras often have a slightly stockier appearance than males. But given how thin these fish are, this is most evident when she’s growing eggs.
Temperament
Silver dollar tetras are non-aggressive fish that get along well with each other and tank mates of different species.
In fact, buying silver dollars in groups is vital to their well-being, given that they’re schooling fish that thrive off social interaction with each other.
But you can also expect your silver dollar tetras to get along well with many other types of fish in your tank.
There isn’t much that causes these fish to turn aggressive. Instead, they’d rather hide in vegetation than pick a fight.
Both males and females display similar peaceful temperaments.
Tank Parameters
If you’re ready to be the proud owner of silver dollar tetras, read on to learn about the tank parameters these fish require.
Minimum Tank Size
You should get a tank of at least 75 gallons to accommodate five silver dollar tetras. Five is the minimum number of these tetras you should place together, given their schooling nature.
Should you wish to have more than five silver dollar tetras, which your fish will love, you’ll need to factor in an extra ten to 15 gallons per fish.
It’s common to purchase silver dollar tetras from vendors before these fish reach their adult size. So, don’t let smaller-sized tetras fool you into thinking that you can get away with a smaller tank.
Water Parameters
Silver dollar tetras are relatively hardy fish but require the following water parameters to maintain their best health.
Temperature
You should keep your silver dollar tetra’s tank between 75°F to 82°F.
These fish come from warm climates, so they won’t do well in cold environments. Installing a heater is the best way to ensure your aquarium water remains at a consistently warm temperature.
pH
You’ll need to keep the tank water on the acidic side for your silver dollar tetras. They prefer a pH between 5.0 to 7.0.
That means these fish have a higher-than-average tolerance for acidic environments. But they can’t handle alkaline water, given that a neutral pH of 7.0 is the highest they can live in.
You should also look to keep your silver dollar tetra’s water around a hardness of 15 dGH.
Salinity
There’s no need to add salt to your silver dollar tetra’s tank unless your fish are sick.
These fish are from freshwater regions of South America, so too much salt will kill them. Still, you may need to use a salt solution if your silver dollar develops a condition like ich. When that’s the case, be sure to follow the instructions of the solution to the letter.
Tank Setup
Once your water is ready to receive silver dollar tetras, below are the more visible aspects of their tank you must consider.
Substrate
We recommend using gravel or sand substrate (or a combination of the two) for your silver dollar tetras. Doing so will mirror the type of substrate they’d have in the wild.
For this reason, using a dark brown or black substrate is ideal.
However, you don’t have to worry much about your tank’s substrate. Since silver dollar tetras primarily live at the top of a tank, meaning they won’t be picky about what goes on at the bottom of their aquarium.
Decorations
Decorations can be a nice touch to silver dollar tetra tanks, but any additions mustn’t interfere with your fish’s ability to swim.
Remember, silver dollar tetras grow both long and tall. Plus, they swim in schools. With that in mind, having an open swimming space is more important than packing your tank full of pretty decor.
Nevertheless, silver dollars appreciate some driftwood. You can adorn the bottom of your tetra’s tank with rocks, logs, and caves to mimic their natural habitat.
Placing a cave or pile of rocks high enough to reach the upper proportion of the water column is also helpful for giving your tetras a hiding place.
Plants
Live plants are a double-edged sword when it comes to silver dollar tetras—they serve as important habitat and hiding spaces, but your fish will devour them.
Since you’ll be feeding your silver dollar tetras a high-quality diet without them needing to eat plants, using plants they don’t like the taste of is best. Examples include:
- Hornwort
- Java moss
Silver dollar tetras enjoy heavily planted areas. So, we recommend lining the back and sides of your tank with a thick layer of live plants.
That way, your fish can use the remainder of their tank as open swimming space.
Lighting
Silver dollar tetras don’t need lots of lighting, given that they live in densely vegetated areas in the wild that block out most of the sun.
But since these fish rely on light to know when to be awake and sleep according to their internal circadian rhythm, using a tank light on a low setting is beneficial.
Should you have other fish in your tank that requires higher amounts of light, providing your silver dollar tetras with sections in the aquarium with lots of plants will give them welcome shelter from it.
Filtration
A filter is an essential aspect of a silver dollar tetra tank. Without it, your aquarium will fill with toxins from food and fish waste, killing your tetras faster than you can likely fix it.
For this reason, we encourage you to invest in a high-quality filter. Make sure you can set it on a low current, as this will replicate the tetra’s natural habitat and help infuse the water with oxygen.
Although filters function mostly independently, they still require maintenance. So, set calendar reminders to check your tank filter regularly.
Also, note that filters aren’t a replacement for water changes. You should perform an approximately 25% water change twice per month to reduce the potential toxins in your tank.
Heating
Every silver dollar tetra tank needs a heater. These fish have high-temperature requirements and a small tolerance for temperature fluctuations.
By placing a heater in your tetra’s aquarium, you can feel confident that they’ll enjoy the warm, consistent temperatures they love.
But to be sure, put a thermometer inside your tank for extra certainty.
Diet
Silver dollar tetras are omnivores with vegetarian leanings.
If you place them in a tank with plant species they love, they’ll spend their days eating them until there’s no plant remaining.
Since silver dollars survive mostly off plants in the wild, try to feed them food that’s mostly from vegetarian sources. Some examples include:
- Algae wafers
- Cucumbers
- Seaweed
- Lettuce
In addition, you give them plant-based fish flakes, which are often the easiest choice for busy fish keepers.
That said, silver dollar tetras need small amounts of animal protein on occasion. Some excellent options to feed them include bloodworms and brine shrimp.
The best schedule for silver dollar tetras is two daily feedings.
Let your fish eat all they can in two to three minutes. After that, remove the excess food.
The benefits of doing so are twofold; your tetras won’t become overweight, and their water will have fewer toxins from food debris.
Breeding
New and experienced fish keepers alike can breed silver dollar tetras, given how easy it is to get them to spawn in captivity.
For starters, you’ll need a separate breeding tank that’s 40 to 50 gallons.
Then, increase the water temperature and pH so that it teeters on the highest end of what silver dollar tetras can tolerate. You should also place several floating plants in the tank.
After choosing your favorite male and female, put them in the tank.
The female should soon start growing eggs, and the male will fertilize them. What makes breeding silver dollar tetras so unique among tropical fish is that they don’t typically eat their offspring.
Instead, the female’s eggs will fall to the bottom of the tank, and she and the male will remain happily swimming among the plants at the top.
Regardless, you’re welcome to move the parent fish back to their original tank.
Within a few days, your baby silver dollar tetras will hatch, and you can feed them small flake food and plankton to help them grow.
Common Diseases
Silver dollar tetras don’t have diseases that are specific to their breed. However, they’re susceptible to many illnesses that affect tropical fish.
Parasites, bacterial infections, and fungus are all issues that can impact silver dollar tetras.
The care you put into their water parameters, tank cleanliness, and quarantining new fish have some of the most significant impacts on whether your silver dollar tetras will obtain a disease.
Below are some of the most common conditions that strike them.
Ich
Ich is one of the most prominent parasites that silver dollar tetras are vulnerable to. While fish with robust immune systems often don’t become infected, tetras that don’t can develop small white spots on their bodies.
Catching an ich infestation in its early stages is vital for improving your fish’s chance of survival. You can purchase ich medication to treat the water.
Columnaris
Columnaris is a bacterial infection that makes your silver dollar tetras look like they’re growing mold. It’s a highly contagious disease that results from poor water conditions.
Luckily, treatment is easy with the help of antibacterial medication. Once your fish get rid of columnaris, clean their tank thoroughly to prevent the disease from returning.
Fin Rot
Fin rot is another condition that often comes from bacteria, although fungus is another source. Dirty water, fin nipping, and other fin injuries can spark your silver dollar tetras to develop white edges and stringy tails.
You can treat fin rot by cleaning the tank water and using an antibacterial or antifungal medication.
Gill and Skin Flukes
Gill and skin flukes come in two varieties—Dactylogyrus and Gyrodactylus, both of which are flatworms. These visible parasites latch onto the gills or skin of silver dollar tetras.
They don’t always bother tetras immediately, but they’re dangerous because they can cause bacterial infections. Should your silver dollar tetras have a fluke infestation, you’ll need to treat the tank water with specialized medicine.
Potential Tank Mates
We’ve already established that silver dollars are peaceful and make an excellent choice for community tanks.
But even though your tetras likely won’t pick a fight with their tank mates, they still require a lot of space to swim at the top of their tank.
Therefore, selecting fish companions that live at or towards the bottom of the tank will reduce the chances of a crowded environment.
Some excellent tank mates for silver dollar tetras include:
- Clown plecos
- Kuhli loaches
- Oscar fish
- Cory catfish
The bottom line is that as long as potential tank mates have similar water parameters as silver dollar tetras and don’t have aggressive tendencies, they’ll likely be a great fit.