Argentine Pearl Fish

Argentine Pearl Fish – Care, Tank, Feeding

The Argentine Pearl fish is known for being a relatively easy fish to take care of. It’s also known as a very strange fish. It’s not an overly friendly fish. It’s known for its aggression towards other fish and even its own kind. 

However, it’s hard to imagine a prettier fish for you to add to your aquarium. The Argentine Pearl Fish is a speckled fish, with round, colorful spots decorating its scales from head to tail. The fins, equal in size and shape, are covered in white spots, and the fins themselves are often blue-green.

The female is typically yellow-green with dark stripes throughout. They’re undoubtedly beautiful fish and, unless you are breeding them, they are simple to take care of, so long as you follow a few, specific rules. 

Care: How to Care for Argentine Pearl Fish?

Every fish is a little different. Most fish that frequent aquariums everywhere get along with one another pretty well. However, the drawback of putting breathtakingly pretty fish like the Argentine Pearl in your tank is that they are pretty moody. 


You can probably guess that a fish with the name Argentine in its name is probably from South America. And, you would be right. The water that these fish are native to is a cooler temperature and they prefer the depths of your aquarium when they make themselves at home. 

In fact, their native water often freezes on the surface during the winter months. They are happiest when you keep the water cool and give them plenty of objects to swim in and out of, such as caves or carved wood structures. 

They’ll love decorative items such as sunken ships or underwater castles. 

Standard Length

For an aggressive fish, they aren’t very large. The typical Argentine Pearl Fish will grow to about 3.5” to 2.75” as an adult. In centimeters, they grow to 6 or 7. As an aggressive fish, you should keep only one male along with several females. Thanks to their small size, they don’t need a huge area.

Aquarium Size

As we mentioned above, Argentine Pearl Fish don’t need the aquarium version of a mansion. The minimum size tank should be no less than 15 gallons. Since they enjoy swimming at the very bottom of the tank, you should go a little bigger if you can and give them some objects to swim through. 

According to most estimates, you can have 1 male and either 2 or 3 females per 10.5 gallons of water. 

Water Conditions and Temperature

Argentine Pearl Fish come from a cooler climate and live in cooler waters. During the winter months, the water that they live in freezes over, because they are close enough to the south pole to have the kind of winter you would expect in the northern states. 

You can safely keep your aquarium water as low as 64°F and no higher than 75°F. Somewhere in the middle is probably best but the lower end of the temperature range is perfectly fine as well. 

Argentine Pearl Fish love the cool water. Their origins are the Uruguay River basins and the Lower Parana. You will need to clean their water periodically by conducting partial water changes on a fairly regular basis. Around 50% of their water should be changed out each week. 

Keep in mind, that anything over 75°F is going to bring about noticeable, negative changes in an Argentine Pearl Fish’s behavior and health. 

Argentine Pearl Fish Diet

In their native habitat, these fish survive on insects that land on the water or small crustaceans that they come across. Their favorites are mosquito larvae, white worms, tubifex worms, and daphnia.

Fortunately, you can get your hands on a lot of this stuff or something similar for your aquarium Pearl Fish. They love brine shrimp, blood worms, and tubifex worms. They will eat fish flakes but that’s more out of boredom than any primal desire to eat flakes. It’s not their dish of choice but they will eat it if it’s there. 

Keep their diet interchangeable because Argentine Pearl Fish love variety. 

They are also voracious, with endless pits for bellies. To keep them happy, they need food at least five times per day. 

Behavior and Compatibility

Despite their aggressive nature, there are some other fish types that you can put in the tank with Argentine Pearl Fish. They get along well enough with Rainbowfish, Tetras, and Danios. However, you need to keep only one male and two or three females. 

That’s because they are school fish in nature, so they prefer to swim around with each other and on their own. 

Are Argentine Pearl Fish?

The full name of this particular fish is the Argentine Pearl Fish or the Cynolebias Bellotti. You will often find their name associated with the term Killifish as well, or the Argentine Pearl Killifish. They come from the Rivulidae family of fish. 

It’s easy to confuse this fish with other species since there seem to be so many tiny variations with the name. Pearl fish and killifish are not the same thing but rather used as two terms in a single name.

Are Argentine Pearl Peaceful?

It depends on who their tank mates are. As we mentioned above, Argentine Pearl Fish will often get along with Rainbow Fish, Tetras, and Danios. There are other fish out there that will probably get along with the Argentine Pearl FIsh as well. 

If you want to suppress their aggressive nature as much as possible, there needs to be only one male in the school and a couple or a few females. That will keep the male happy and out of competition with a rival male. It will also keep your Argentine Pearl Fish happy because they prefer to swim in schools. 

All Things Considered

The Argentine Pearl Fish is not very difficult to take care of, although they can be a bit aggressive with other fish. Just be sure to keep only one male and a few females and that should help suppress their aggressive natures. Other than that, they love cool water and swimming along the bottom of the tank, so be sure to give them some stuff to swim through.