Top 10 Stunning Nano Fish for your Next Small Fish Tank

Top 10 Gorgeous Nano Fish for Your Next Small Fish Aquarium

Nano fish tanks are very popular for their beauty and compact size, but it can be challenging to find animals that are tiny enough to comfortably live in them. If you only have room for a 5- to 20-gallon aquarium, check out our top 10 small aquarium fish that are known for their vibrant colors, fun personalities, and unique appearances.


1. Celestial Pearl Danio

Danio margaritatus

Also known as the galaxy rasbora or CPD, this little fish has been extremely popular ever since its discovery in 2006. It is a miniature trout that was originally from Southeast Asia. It has shiny golden spots and bright orange tails. These schooling fish are a bit more expensive than the average CPD at $6-10, so you might want to save some money and get at least six. CPDs are known to be a bit shy, so make them feel safer by increasing the size of their group and providing plenty of decorations and aquarium plants as cover. CPDs prefer to be fed in the middle of the water, not at the bottom or top, so make sure you choose small, slow-sink foods like frozen cyclops, baby brine shrimp, daphnia, and baby brine shrimp.

2. Chili Rasbora

Boraras brigittae

Chili rasboras get their common name from the fiery red color they display as full-grown adults, but most of time you see juveniles at the fish store that are much paler in appearance. You will see a change in their color six months after they are fully grown if you take the time to care for them. They are the smallest of our fish and can grow to approximately 0.8 inches (2 cm) in size. Their profile is very slim. They look best when there are at least 10 brigittae rasas in a school, and they are surrounded by lush green plants. As with the celestial pearl danios, feed them tiny foods that swirl midwater in the aquarium, such as baby brine shrimp, crushed flakes, and Easy Fry and Small Fish Food.

3. Pygmy Corydoras

Corydoras pygmaeus

The adorable pygmy pygmy korydoras, which measure in at 1-inch (2.5cm), are just as cute as the baby cory cats. They are a good pair with previous schooling fish, as they can use their whisker-like barels to pick up any crumbs and clean them up. They enjoy eating just about any fish food, including sinking wafers and Repashy gel food. Pygmy corys, a schooling fish, require at least six fish to feel comfortable. However, if they are difficult to find in fish shops, you might consider other dwarf corydoras species like C. habrosus or C. hastatus. See our care guide for more information about cory catfish care.

4. Kuhli Loach

Pangio kuhlii

Although this bottom dweller can grow up to 4 in (10 cm) in size, it is not a micro fish. However, their slim, eel-like bodies mean that they don’t produce much bioload. This oddball creature is great for keeping with other nano fish because of its peaceful appearance and calm demeanor. Kuhli loaches can be a great fish for beginners as they aren’t picky about water conditions or food preferences. Check out the P. oblonga black kuhli and P. anguillaris silver kuhli, which offer additional color options. Learn all about them in our full care guide.

5. Green Neon Tetra

Paracheirodon simulans

As a slightly smaller cousin of the regular neon tetra, Paracheirodon simulans only gets 1-1.25 inches (2.5-3 cm) long and doesn’t have much of a red stripe. Instead, the body is covered with a bright blue/green horizontal stripe that shines brilliantly in dim lighting. Although they can live in slightly acidic waters, they thrive in normal water conditions for a tropical community aquarium. Keep a minimum of 6-8 green neon Tetras in your aquarium and give them lots of slow-sinking, small fish foods. Also, many of them are caught from the wild and may come with fin rot or ich, so make sure to quarantine them after purchase to prevent disease from spreading to your other aquariums.

6. Clown Killifish

Epiplatys annulatus (male is above and female is below)

The rocket killifish or banded panax is famous for its dark vertical stripes and brilliant tail. This tail looks like a rocket’s flame. The males have all the amazing colors, whereas the females have the banded body with a clear tail. Because the guys can be a bit territorial with each other, aim for a group with a ratio of 1 male for every 2-3 females. This 1.5-inch (3.8 cm), top-dwelling fish prefers to hang out in the upper third of the aquarium, so use a tight-fitting lid with all the holes plugged up so that they won’t jump out. Offering them floating food such as frozen tubifex and flakes will encourage them to start spawning. Read our article about clown killies for more details.

7. Ember Tetra

Hyphessobrycon amandae

This 0.8-inch (2 cm) tetra from Brazil boasts a bright orange-red body that lights up any aquarium, especially those with lush, green plants. They are hardy and will do well in a smaller tank as well as in a school of 20-30 fish in an aquarium larger than a nano tank. Unlike many nano fish, ember tetras are relatively outgoing and eagerly eat from all levels of the aquarium. Feast them with floating or slowly sinking foods such as Hikari Micro Pellets, Xtreme Nano pellets and frozen daphnia.

8. Panda Guppy

Poecilia reticulata

Finally, we have a livebearer (or fish that bears live young) on our list. Guppies are very well-known in the hobby, but they usually grow up to 2.5 inches (6 cm) long. Panda guppies have a smaller size and a shorter tail. Males are approximately 1 inch (2.5cm) in length, while females are about 1.75-2cm (4-5cm). They can be found in striking colors of blue, black and silver.

We find them less fussy than other fancy guppies and even kept them in an outdoor pond during warmer seasons. If your water is soft, you might consider adding Wonder Shells to your aquarium or Seachem Equilibrium. Fortunately, they are easy to feed and readily eat at all levels of the aquarium, so you don’t need to get a bottom dweller to clean up your nano tank. Panda guppies have been a favourite variety of ours, so give them a chance. For more information, see our complete guppy care guide.

9. Spotted Blue Eye Rainbowfish

Pseudomugil gertrudae

Pseudomugil rainbowfish such as Gertrude’s Rainbowfish are a good choice if you’ve always loved rainbowfish and don’t have the space to keep them. This 1.5-inch (3.5cm) species is beautiful with bright blue eyes, black spots, and a yellow body. Males are more colorful that females. You should get one male per two females to ensure the boys can display their best colors and unique sparring routines. Similar to the guppies they prefer higher pH and GH. However, they can live in a wide temperature range.

As a surface-dwelling fish that likes to swim in the top half of the aquarium, get a tight-fitting lid to prevent jumping and feed lots of floating foods like flakes and freeze-dried foods. While Pseudomugil rainbowfish are very lively and beautiful, they tend to have a shorter lifespan, so consider breeding them by using dense floating plants like guppy grass or spawning mops made out of yarn.

10. Borneo Sucker Loach

Gastromyzon sp.

We also have an algae eater to help you keep your nano fish tank healthy. Gastromyzon is a genus of hillstream loaches. They are usually 2 inches (5 cm) long and shaped like tiny stingrays or flounders. Like their larger cousin, the reticulated hillstream loach, they enjoy cleaning off driftwood, scavenging for leftovers, and of course eating algae. They can be kept in normal community tank parameters, but also have the ability to tolerate the cooler temperatures of an unheated aquarium. Borneo sucker loaches can show some territorial behavior toward their own kind, so either get one individual or a group of three or more.

These fish are not available at your local fish shop. We recommend you check out these online retailers. All the best with your nano-tank and have fun in nature.