Best Fish for a Small Tank: Ideal Species for Limited Space

So you’re interested in owning fish — congrats! Fishkeeping is a gratifying hobby. But what do you do if you have limited space? Keeping fish requires a big enough tank for your finned friends to thrive — plus, you need a few essential tank maintenance items. 

Luckily, there are options. Instead of swimming through the web and seeking the best fish for a small tank, we’ve already done it for you. Let’s dive in!

24 Best Fish for a Small Tank

Here are the best fish for a small tank — ranked from smallest to “largest.”

1. Chili Rasbora

The Chili Rasbora is a tiny firecracker of a fish, with vibrant red hues that stand out in any aquarium. They’re peaceful, schooling fish perfect for small, planted tanks.

• Adult size: 0.8 inches (20 mm)
• Minimum tank size: 5 gallons (19 liters)
• Life expectancy: 4-6 years
• Difficulty: Moderate

2. Scarlet Badis

The Scarlet Badis is a tiny, brightly colored fish with a big attitude. They can be shy, but their stunning red hues make them a standout in any nano tank.

• Adult size: 1 inch (25 mm)
• Minimum tank size: 5 gallons (19 liters)
• Life expectancy: 3-4 years
• Difficulty: Moderate

3. Pea Puffer

Pea Puffers are small but mighty, with big personalities packed into their tiny bodies. They’re fun to watch but can be a little feisty, so keep an eye on tank mates.

• Adult size: 1 inch (25 mm)
• Minimum tank size: 5 gallons (19 liters)
• Life expectancy: 4 years
• Difficulty: Moderate

4. Celestial Pearl Danio

Often called the “galaxy rasbora,” the Celestial Pearl Danio is a tiny fish with a big reputation. Their speckled, celestial pattern gives them a starry night look, making them a stunning addition to any tank.

• Adult size: 1 inch (25 mm)
• Minimum tank size: 5 gallons (19 liters)
• Life expectancy: 3-5 years
• Difficulty: Moderate

5. Pygmy Corydoras

Pygmy Corys are tiny, active little guys that are constantly on the move, zipping around the tank. They’re great for nano tanks and get along well with other small fish.

• Adult size: 1 inch (25 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 3-5 years
• Difficulty: Easy

6. Endler’s Livebearer

Endler’s Livebearers are like the cooler, rarer cousins of guppies. They’re brightly colored, breed easily, and add tons of activity to a community tank.

• Adult size: 1.5 inches (38 mm)
• Minimum tank size: 5 gallons (19 liters)
• Life expectancy: 2-3 years
• Difficulty: Easy

7. Bumblebee Goby

Tiny but eye-catching, the Bumblebee Goby sports black and yellow stripes that give it its distinctive look. While they’re small, they do require brackish water, which can make their care a bit trickier.

• Adult size: 1.5 inches (38 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 3 years
• Difficulty: Moderate

8. Pygmy Gourami

The Pygmy Gourami is a shy yet beautiful addition to any small aquarium. Its peaceful demeanor and vibrant colors make it a popular choice for peaceful community tanks.

• Adult size: 1.5 inches (38 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 3-4 years
• Difficulty: Moderate

9. Black Phantom Tetra

With their sleek black bodies and a faintly transparent finish, Black Phantom Tetras are both mysterious and elegant. They do best in groups and can be surprisingly active once settled in.

• Adult size: 1.5 inches (38 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 5 years
• Difficulty: Easy

10. Neon Tetra

Neon Tetras are the OGs of small community fish, known for their brilliant blue and red stripes. They’re schooling fish, so the more, the merrier! Their flashy colors make them one of the most popular fish out there.

• Adult size: 1.5 inches (38 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 5-10 years
• Difficulty: Easy

11. Fancy Guppy

Fancy Guppies are the fashionistas of the fish world, with their flowing tails and endless color varieties. They’re easy to care for, making them a popular choice for beginners. Plus, they breed like crazy, so get ready for baby guppies!

• Adult size: 2 inches (50 mm)
• Minimum tank size: 5 gallons (19 liters)
• Life expectancy: 2-3 years
• Difficulty: Easy

12. Harlequin Rasbora

Harlequin Rasboras are easygoing, hardy fish that add a splash of color to any tank with their copper-orange hue. They’re a peaceful schooling species that loves swimming in groups.

• Adult size: 2 inches (50 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 5-6 years
• Difficulty: Easy

13. Panda Corydoras

The Panda Cory is as cute as its namesake, with striking black and white patches that make it stand out. They’re peaceful, playful bottom-dwellers who love to scavenge and keep your tank tidy.

• Adult size: 2 inches (50 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 5-7 years
• Difficulty: Easy

14. Betta Fish

Bettas are known for their stunning fins and bold personalities. They’re solitary creatures who prefer their own space, but their vibrant colors and flowing fins make them a star of any aquarium.

• Adult size: 2.5 inches (64 mm)
• Minimum tank size: 5 gallons (19 liters)
• Life expectancy: 2-4 years
• Difficulty: Moderate

15. Mickey Mouse Platy

Named for the famous mouse thanks to its tail markings, the Mickey Mouse Platy is a fun, hardy fish that’s perfect for beginners. They come in many bright colors and love to peacefully swim around their tank.

• Adult size: 2.5 inches (64 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 3-5 years
• Difficulty: Easy

16. Peacock Gudgeon

The Peacock Gudgeon is a brightly colored, peaceful fish that loves to explore the nooks and crannies of a well-decorated tank. Their playful nature makes them a joy to watch.

• Adult size: 2.5 inches (64 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 3-5 years
• Difficulty: Moderate

17. Hatchetfish

Hatchetfish have a unique, “flying fish” shape, and they love to hang out at the top of the tank. Known for their jumping abilities, make sure you have a tight-fitting lid!

• Adult size: 2.5 inches (64 mm)
• Minimum tank size: 20 gallons (76 liters)
• Life expectancy: 5 years
• Difficulty: Moderate

18. Dwarf Gourami

These vibrant little fish pack a lot of color into a small package. Dwarf Gouramis are peaceful and thrive in well-planted tanks, where they can explore their surroundings.

• Adult size: 2-3 inches (50-76 mm)
• Minimum tank size: 10 gallons (38 liters)
• Life expectancy: 4-5 years
• Difficulty: Moderate

19. Knight Goby

The Knight Goby is a little warrior that loves to perch and observe its kingdom (your tank). With its unique speckled pattern, it’s sure to catch your eye. These fish prefer brackish water, so they’re a bit different from your average freshwater fish.

• Adult size: 3 inches (76 mm)
• Minimum tank size: 15 gallons (57 liters)
• Life expectancy: 4-5 years
• Difficulty: Moderate

20. Tiger Barb

Tiger Barbs are feisty, striped fish that love to school and show off their bold patterns. While playful, they can get a bit nippy, so make sure to pair them with suitable tank mates.

• Adult size: 3 inches (76 mm)
• Minimum tank size: 20 gallons (76 liters)
• Life expectancy: 5-7 years
• Difficulty: Moderate

21. Molly

Mollies are like the laid-back surfers of the fish world — chill, colorful, and adaptable. They thrive in freshwater and brackish setups and come in many varieties like black, dalmatian, and balloon mollies.

• Adult size: 4 inches (102 mm)
• Minimum tank size: 20 gallons (76 liters)
• Life expectancy: 3-5 years
• Difficulty: Easy

22. Scissortail Rasbora

With its sleek body and distinctive forked tail, the Scissortail Rasbora is fast and graceful. They’re active swimmers and do best in schools where they can dart around together.

• Adult size: 4 inches (102 mm)
• Minimum tank size: 20 gallons (76 liters)
• Life expectancy: 5-7 years
• Difficulty: Moderate

23. Kuhli Loach

Kuhli Loaches are like little underwater snakes, constantly burrowing and wriggling through the substrate. They’re shy but incredibly entertaining once they get comfortable in their environment.

• Adult size: 4 inches (102 mm)
• Minimum tank size: 20 gallons (76 liters)
• Life expectancy: 10 years
• Difficulty: Moderate

24. Pearl Gourami

The Pearl Gourami is like a floating jewel, with shimmering spots covering its body. They’re calm and can be quite friendly, even coming to the top of the tank to greet you when it’s feeding time.

• Adult size: 4-5 inches (102-127 mm)
• Minimum tank size: 30 gallons (114 liters)
• Life expectancy: 4-6 years
• Difficulty: Moderate

Hooked on Aquariums? Level Up With Aquabuildr!

Just because the tank is small doesn’t mean you have only a few options. If two or three… or four fish caught your eye, we get it — there are many beautiful species out there. But if you’re wondering whether they can be tank buddies, don’t fret — we have an easy solution for you. 

Our Aquabuildr app specializes in intelligent and innovative aquarium building. Imagine having all the essential tools at your fingertips — tailored tank sizes, intelligent alerts for fish compatibility, and easy monitoring to ensure your aquatic buddies are living their best lives. With Aquabuildr, you can confidently create and maintain a thriving aquarium without the guesswork.

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