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Looking to stock your nano aquarium with beautiful, lively species? Whether you're working with a 5-gallon desktop tank or a sleek 10-gallon setup, nano fish—also known as small freshwater fish—are the perfect stars of your compact aquatic world. These small aquarium fish are known for their bright colors, peaceful temperaments, and compatibility with small tanks. In this guide, we’ll walk you through the top 10 types of small fish ideal for small aquariums.
Let’s dive into the most popular and beginner-friendly nano fish that will elevate your aquascape while keeping your maintenance low and enjoyment high.
What Are Nano Fish?
Nano fish are small fish species that typically stay under 1.5 to 2 inches in length. Because of their size, they are perfect for nano aquariums, which are generally tanks under 20 gallons in capacity. Fish for small tanks must be hardy, peaceful, and capable of thriving in limited space—making nano fish the go-to choice for hobbyists with limited room.
1. Chili Rasbora (Boraras brigittae)
- Size: ~0.7 inch
- Tank Size: 5+ gallons
- Temperament: Peaceful
- Ideal Temp: 72–82°F
One of the tiniest nano fish, Chili Rasboras are fiery red schooling fish that thrive in heavily planted tanks. They prefer soft, acidic water and feel safest in groups of 8 or more. Their small size and low bioload make them ideal for nano aquariums.
2. Ember Tetra (Hyphessobrycon amandae)
- Size: ~0.8 inch
- Tank Size: 5+ gallons
- Temperament: Peaceful
- Ideal Temp: 74–82°F
Glowing like flickers of fire, Ember Tetras add warmth and life to your small tank. These small freshwater fish love to swim in groups and are incredibly beginner-friendly. A well-planted environment enhances their color and behavior.
3. Celestial Pearl Danio (Danio margaritatus)
- Size: ~0.75 inch
- Tank Size: 10+ gallons
- Temperament: Peaceful, shy
- Ideal Temp: 73–79°F
Also known as Galaxy Rasboras, these nano fish resemble miniature galaxies with their pearly white spots and red-orange fins. Celestial Pearl Danio enjoy dense vegetation and calm tank mates.
4. Pygmy Corydoras (Corydoras pygmaeus)
- Size: ~1 inch
- Tank Size: 10+ gallons
- Temperament: Social and peaceful
- Ideal Temp: 72–78°F
These adorable bottom dwellers are active and social. Unlike larger Cory Catfish species, Pygmy Corys also swim mid-level in schools. They’re great at keeping your substrate clean while being playful and peaceful.
5. Fancy Guppy (Poecilia reticulata)
- Size: ~1.2 to 1.4 inches
- Tank Size: 5+ gallons
- Temperament: Peaceful
- Ideal Temp: 72–82°F
Fancy Guppies are a long-time favorite among aquarists. Their flowing tails and wide range of colors bring beauty and activity to small tanks. They are livebearers and easy to breed, making them excellent for hobbyists.
6. Rainbowfish (Dwarf Varieties)
- Size: ~1.5 to 2 inches
- Tank Size: 10+ gallons
- Temperament: Peaceful and active
- Ideal Temp: 74–80°F
Dwarf rainbowfish offer dazzling color shifts in the light. They are great schooling fish for nano tanks, especially when kept in groups of six or more. Their shimmering scales and calm nature make them fantastic community fish.
7. Golden Pencilfish (Nannostomus beckfordi)
- Size: ~1.5 inches
- Tank Size: 10+ gallons
- Temperament: Calm and shoaling
- Ideal Temp: 72–80°F
With their golden bodies and black horizontal stripes, Golden Pencilfish add elegance to the mid-to-surface levels of your tank. They thrive in soft water with plenty of plants and prefer calm tank mates.
8. Clown Killifish (Epiplatys annulatus)
- Size: ~1.2 inches
- Tank Size: 5+ gallons
- Temperament: Peaceful
- Ideal Temp: 72–78°F
Clown Killifish are surface-dwelling gems known for their rocket-like shape and bold coloration. They do well in nano setups with floating plants and soft lighting. A secure lid is recommended, as they may jump.
9. Rainbow Shiner (Notropis chrosomus)
- Size: ~2 inches
- Tank Size: 15+ gallons
- Temperament: Peaceful
- Ideal Temp: 64–74°F
Native to the U.S., Rainbow Shiners flash with iridescent blues, purples, and pinks. While slightly larger than most nano fish, they are perfect for slightly bigger small tanks. Keep them in groups of 6+ for best results.
10. Dwarf Gourami (Trichogaster lalius)
- Size: ~2 inches
- Tank Size: 10+ gallons
- Temperament: Peaceful, semi-territorial
- Ideal Temp: 76–82°F
Dwarf Gouramis are centerpiece fish for nano tanks. Their vibrant colors and graceful swimming style make them a joy to observe. Males can be territorial, so house with caution in small spaces.
Nano Aquarium Setup Tips
To help your nano fish thrive, follow these essentials:
- Choose the Right Tank Size: 5 to 10 gallons works well for most small freshwater fish, but the more space, the better.
- Filtration Matters: Use sponge filters or low-flow internal filters that don’t create too much current.
- Lighting: Opt for low-to-medium lighting, especially for planted tanks.
- Aquascaping: Add live plants, driftwood, and caves to create a natural feel and reduce stress.
- Regular Maintenance: Smaller tanks can experience parameter swings, so weekly water changes (20–30%) are crucial.
Conclusion
When done right, a small aquarium can be just as vibrant and full of life as a large tank. With the right types of small fish, you can build a dynamic, colorful, and low-maintenance aquascape that’s perfect for desktops, small apartments, or as a peaceful addition to your home or office.
Each of the nano fish on this list brings something unique—whether it's color, behavior, or personality. Choose fish that are compatible in terms of temperament and water parameters, and you’ll have a stunning tank to enjoy every day.
Visit Splashy Fish tropical fish store to buy these freshwater fish for sale online or at our aquarium store in Virginia for more betta fish for sale, freshwater invertebrates for sale, and aquarium supplies.
Nano Fish Frequently Asked Questions (FAQs)
How many nano fish in a 10-gallon tank?
You can typically keep 6 to 10 nano fish in a 10-gallon tank, depending on the species, filtration, and tank setup. For small schooling fish like Chili Rasboras, Ember Tetras, or Celestial Pearl Danios, a group of 6–8 is ideal. If you mix species, be mindful of their bioload and ensure they occupy different swimming levels (top, mid, bottom). Always avoid overcrowding and monitor water quality closely.
How often should I feed nano fish?
Feed nano fish once or twice daily with high-quality micro pellets, flakes, or frozen foods. Give them only what they can consume within 2 minutes to avoid water pollution. Many nano species like Clown Killifish or Scarlet Badis prefer live or frozen food, so rotating the diet helps maintain their health and color. A fasting day once a week is also beneficial for digestion.
Can these nano fish live together in a tank?
Yes, most nano fish can live together in a peaceful community tank, especially if they have similar water parameter needs and temperaments. For example, Ember Tetras, Pygmy Corydoras, Celestial Pearl Danios, and Fancy Guppies are great companions. Avoid mixing aggressive or very shy species in confined spaces. Use plants, hiding spots, and proper space distribution to minimize stress and territorial behavior.
