What Is the Smallest Aquarium Fish?

If you have a small tank, you’re probably looking for tiny fish to pet.

Many fish species do well in as little as 3 gallons of water. Many nano fish are either shoaling or schooling species, which is perfect for beginners.

They’re easier to maintain and look after. Plus, small fish are super-friendly!

Keep reading if you want to find out what is the smallest fish for your aquarium.

What Is the Smallest Aquarium Fish?

The smallest aquarium fish is the Indonesian Super Dwarf fish, measuring only 0.41 inches (1.04 cm). It can easily live in a 3-gallon fish tank. This fish holds the world-record title of being the smallest nano fish species in the world.

It’s also the smallest freshwater fish for a home aquarium.

Indonesian Superdwarf fish - paedocypris-progenetica

To put things into perspective, the adult fish is as minuscule as an adult mosquito. They were originally discovered in the tropical rainforests of New Guinea. The Indonesian Superdwarf is a shoaling fish that can comfortably live in a 3-10 gallon tank.

Also known as Paedocypris Progenetica, the nano fish is mostly found in the black tea swamps of Southeast Asia. The dark black tea swamps are extremely acidic from the decomposing tree leaves. This is why the Indonesian Superdwarf fish love acidic water with a pH of 3.

They have extremely thin, slender, and transparent bodies with pelvic fins.

The mature males grow as big as 0.39 inches. They have clutching pads on their fins to grab females during mating. If you’re keeping them in your aquarium, prepare an acidic, blackwater planted tank.

However, its small size makes it a little difficult to look after. These nano pets are extremely fragile to the pH of the tank. Maintaining such low levels of acidity can be hard, especially if you’re a beginner.

Therefore, keep in mind that the Indonesian Supedwarf is an expert-level fish. In fact, the species are facing extinction threats due to its ecosystem destruction in the wild.

Other Small Freshwater Aquarium Fish

While the Indonesian Superdwarf is a high-maintenance fish, there are many other aquarium-friendly micro fish.

Nano fish that don’t grow beyond 2 inches look extremely attractive and dainty. They can add streams of colors to an aquarium.

Petting small fish has its share of advantages. Most of them are schooling fish and thrive well in smaller tanks.

They’re also peaceful and co-exist with other similar-sized aquatic animals. Many are also great jumpers and stay on the upper levels of the tank.

Here’s a comprehensive list of species for micro fish keeping.

Dwarf Pencilfish

This one grows up to 0.98 inches or 2.5 cm. Extremely active with a bubbly personality, Dwarf Pencilfish can light up your aquarium beautifully. Since they are schooling fish, it’s best to introduce them in groups of 5-10.

Alone or isolated, these micro fish can feel lonely and stressed. In a group, they feel confident and secure and are much more active.

They prefer slightly cooler water temperatures from 73-84 Degrees F with a pH of 5.7-7. Dwarf Pencilfish feel most at home in dark, blackwater habitats. While petting them, keep the lighting dim and the water slightly acidic.

They also thrive well in low currents so keep the filtration modest and slow. You need at least 10-gallons of water for the fish to play and thrive well.

Make sure not to add them to a newly cycled tank. These species aren’t hardy enough to tolerate the fluctuating mineral levels.

Introduce them only when your aquarium has matured or is well established. If you do light up the aquarium, keep floating plants to absorb excess light. This will maintain a home-like, dark substrate for the fish to relax.

Pygmy Sunfish

The Gulf Coast Pygmy Sunfish is a stunning micro pet fish for your home aquarium. It belongs to the Elassoma family and is the smallest of the seven species. The fish can grow up to 1 inch (2.54 cm). However, most stop growing at 0.98 inches (2.48 cm).

What’s intriguing about this sunfish is that it was discovered only a decade ago. They’re extremely beautiful and dainty with rich hues of electric blue.

Keep them in a mature tank that’s at least 5 gallons or more. They prefer temperatures between 68 and 74.3 degrees F with a pH of 6.5-7.5.

The dominant male sunfish colors up in electric blue and black when it tries to claim its territory. Keep them in a densely planted aquarium with soft water. Since they’re wild-caught, pygmy sunfish can survive in a wide range of water parameters.

They do well in neutral and slightly alkaline waters of 7-8 pH as well. Since they’re hardy survivors, Pygmy sunfish require low oxygen levels. You won’t have to worry much about filtration while petting them.

A 5-gallon tank can only accommodate two to three sunfish. For a comfortable habitat, keep them in at least 10 gallons of water.

But, if you want to introduce tank mates, 20 gallons is ideal. However, the one thing you need to take care of is a constant supply of live food.

Pygmy sunfish require live foods like insects and worms to thrive and spawn. Keep them in slow-moving low currents as they’re peaceful species.

Green Neon Tetra

Neon tetras are a popular, attractive micro fish that grow up to an inch (2cm). Native to South America and Orinoco River Basins, they are one of the easiest aquarium fish. However, the green neon tetras can get bigger, so keep them with similar-sized species.

They are a schooling species that thrive well in a 10-20 gallon tank. Their ideal tank mates are either their own species or other micro fish. Keep the water temperature between 73 and 85 degrees F with a pH of 5.5-6.

Green neon tetras are extremely peaceful and attractive. With bold blue-green patterns, they can add a colorful streak to your aquarium.

They survive well on a mixed diet of live food and pellets. However, even when they’re easy to care for, keep a lookout for Neon Tetra disease. They also have a moderate lifespan of 2-3 years or more, which makes them great for a home aquarium.

Chili Rasbora

Also known as Mosquito Rasboras, these peaceful are native to the Indonesian rivers. They have striking red and black patterns to add a unique shade to your aquarium.

Chili Rasbora can grow up to 0.78 inches (2cm). As a schooling fish, they look beautiful in large groups of 10-12.

They thrive well in temperatures between 75 and 84 degrees F with a pH of 4.5-6.8. Since they come from a blackwater habitat, they prefer live plants in the tank.

Indian almond leaves or floating plants are perfect to keep the tank dim and relaxing.

Chili Rasbora is sensitive to the pH of the tank. Therefore, make sure to maintain high acidity at all times. Don’t introduce them to a new tank as they can’t tolerate mineral changes. Keep them in a mature 5-gallon tank with stable water chemistry.

You can also pair them up with similar small-sized fish species like small Caridina and pygmy Corydoras.

Chili rasboras love feeding on live worms like mini bloodworms, Cyclops, and daphnia. As long as there is good filtration and acidic water levels, the species will thrive well.

Dracula Minnow

Minnows are absolute tank delights! They are active swimmers and can bring life to a dull home aquarium. Dracula minnows are micro fish that grow up to 0.65 inches (1.67 cm).

Perfect for 5-gallon tanks, these minnows have intricate, scaly patterns on their bodies.

Maintain a pH of 6.5-7.5 as these tiny swimmers prefer slightly acidic to slightly alkaline water. Dracula minnows prefer slightly cooler temperatures of 66-78.8 Degree F.

They were recently discovered in 2007 in the water bodies of Myanmar and Burma. The species are known for their unusual teeth and large eyes.

Their teeth are quite intriguing. They’re basically fangs created from protruding bones that stick out from their jaws. However, as scary and bizarre as they may seem, these minnows are peaceful.

Feed them micro worms and daphnia, and always introduce them in schools.

Dario Dario

These species are just as funky as their name. Dario Dario is small Indian fish species, native to the Brahmaputra river.

They grow up to 0.78 inches (2cm). Extremely beautiful with vibrant colors, Dario Dario is a good pick for beginners.

The male Danios light up with the most color just before mating. In the end, the most colorful male Dario Dario wins the lady.

All in all, they’re super fun to breed and look after. The best pH range for Dario Dario is 6.8-7.8 with temperatures of 68-78.8 Degrees F.

In a community tank, they can get slightly aggressive and territorial. When petting Dario Dario, the males should especially be kept in separate tanks.

You can also create boundaries inside the same tank to avoid conflicts.

Coconut shells and driftwood act as great hiding places or “caves” for Dario Dario. Try to pet them as single species and don’t include other smaller fish.

Dario Dario is micro-predatorial so you might be able to avoid a battle. All in all, they’re a wonderful addition to a house aquarium!

So that sums up the smallest fish species for a home aquarium.

Keeping micro fish is always easier and convenient than petting large fish. And, since they love traveling in schools, your aquarium will always bustle with life!

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