Top 10 Fish for a 10 Gallon Tank
A 10 gallon or 40-litre tank is one of the most popular and easiest-to-manage tanks for aquarium starters. Choosing the right fish and a specific tank makes a difference in the ecosystem, and a consistent environment in the tank means the owner doesn’t get into the battle for stress, disease, or cloudy water. The good news is there are plenty of colorful and peaceful fish species that stay small and live happily in the aquarium tank.
We have selected our top 10 fish, a comparison table, and combinations. Also, we have highlighted the fish you should never put in a 10 gallon tank.
Best Fish for a 10 Gallon Tank
A 10 gallon tank should have small, peaceful species that are under 5 cm, like bettas, tetras, rasboras, corydoras, and guppies. They don’t get large in size and are good for the 40-litre aquarium tank.
| Fish | Size | Group | Temp (°C) | Care | Temper |
|---|---|---|---|---|---|
| Betta | 5–8 cm | Alone | 24–28 | Easy | Aggressive |
| Tetra | 3 cm | 5–10 | 23–29 | Easy | Peaceful |
| Neon Tetra | 5 cm | 5–10 | 22–26 | Easy | Peaceful |
| Rasbora | 2 cm | 5–10 | 22–28 | Easy | Peaceful |
| Guppies | 2-3 cm | 5–10 | 22–28 | Easy | Peaceful |
| Corydoras | 3-5 cm | 4–7 | 22–26 | Easy | Peaceful |
| Danio | 2-4 cm | 5–10 | 21–26 | Easy | Peaceful |
| Minnow | 3-4 cm | 6-8 | 18–22 | Easy | Peaceful |
| Catfish | 5–6 cm | 2–5 | 22–26 | Easy | Peaceful |
| Gourami | 3-6 cm | 2–3 | 24–27 | Easy | Peaceful |
Check These Before Choosing Fish for a 10 Gallon Tank
A 10 gallon aquarium tank provides limited space and water, so mistakes will show results fast. Check these 5 factors before you buy fish or a tank.
Size
Fish are sold as juveniles in the aquarium store. Always research or ask the store manager about the age of the fish. Pick the size that stays under 2 inches. Larger fish will make the aquarium crowded, busy, and messy.
Space
A small tank means a small room to play. Fast swimmers like zebra danios need more space.
Schooling
Tetras, rasboras, and corydoras are safe in groups, and they actually feel safe and stay in groups. Keeping 2-3 in a tank makes them feel stressed. Keep at least 5-6 at a time.
Filtration
Don’t add more fish to the tank. More fish = More Waste. Keep 5-6 fish at a time to maintain a healthy environment in the aquarium and reduce bioload.
Water Parameters
Always keep fish that share the same temperament, temperature, and pH range. It will help keep the fish healthy and moving.
10 Best Fish for a 10-Gallon Tank
1. Betta
It’s a classic piece for all sizes of tanks. Flowing fins, vibrant colors, and a dominating personality make bettas different. Adding this to the tank gives them more space compared to tiny bowls. Keep a male betta alone or with peaceful species like Corydoras that are bottom dwellers. Normal filtration, a heater, plants, or almond leaves will help improve the health of the betta. Avoid fin-nipping fish with bettas.
2. Tetra
Small and won’t grow larger than 1.5 inches. One of the best fish for a 10-gallon tank. Tetras are hardy, and their colors look stunning with green plants. Keep 6-10 in a tank. Feed flakes, small or micro pellets, and use a dark base or background to highlight the tetra colors.
3. Neon Tetra
The most common and recognizable aquarium fish, with a red tail and a blue stripe on the body. A solid choice for less maintenance. They are sensitive to water changes, so always keep them in a cycled tank. Keep 8-10 in a tank.
4. Rasbora
The size will be no more than 1 inch. Rasboras are the best nano fish. Their red bodies make the tank look vibrant with a group of 8-10 fish. Don’t overload the tank with fish. They are best in a planted aquarium setup. Feed small micro pellets or flakes.
5. Guppies
With a variety of colors and species, they are extremely hardy and one of the top picks for beginners. Keep 5-10 in groups, and they breed constantly.
6. Corydoras
Tiny, small catfish that usually swim in the middle or bottom of the tank. Very playful and peaceful, they need a smooth substrate to protect their barbels. Feed sinking pellets or algae wafers.
7. Danio
Danios come in multiple colors, with bodies featuring stripes or pearl spots. They are favorite fish for planted tanks. They are shy and need plants for cover. Feed micro pellets and keep 8-10 at a time in a tank.
8. Minnow
Minnows are hardy fish, and as far as I know, they don’t need a heater or any specific setup. They will live at room temperature. Keep 6-10 together in a tank, and don’t mix them with other species. Feed micro pellets and flakes.
9. Catfish
Algae eaters in tanks. A good choice compared to plecos because plecos grow larger. An algae setup is good for catfish, and you can keep 3-5 in a tank. Feed algae wafers to keep catfish healthy.
10. Gourami
Keep a small group of 3-5 fish in a heavily planted tank. Sometimes they become territorial, so keep hiding spaces in the tank to reduce conflict and stress among the fish. Feed pellets, worms, or small insects.
5 Fish Combination for a 10 Gallon Tank
Don’t know how many fish to put in the 10-gallon tank? Try one of these combinations, tested and safe for the bioload.
| Setup | Fish | Best for |
|---|---|---|
| Betta | 1 betta + 3 corydoras + 2 snails | Fish with bottom activity |
| Nano | 6 ember tetras + 3 corydoras | Peaceful and colorful |
| Red and Green Planted | 6 rasboras + 3 corydoras | Aquascapes |
| Guppies | 6 guppies + 4 corydoras | Bright and active |
| Normal | 6 minnows | Room-temperature |
Fish Species to Avoid in a 10 Gallon Tank
These popular fish species are best-selling for small tanks, but they grow quickly, are messy, and some of them are hard to keep together with the same or different species.
| Fish | Adult size | Why to avoid |
|---|---|---|
| Goldfish | 4–10 in (15–30 cm) | Waste, messy and need 20+ gallon tank |
| Pleco | Up to 20+ in (60 cm) | Large in size |
| Angelfish | 2-4 in (15 cm) | Eats small fish species |
| Oscar | 5-10+ in (30+ cm) | 70+ gallon tank |
| Tiger Barb | 2-3 in (7.5 cm) | Fin-nipper |
| Rainbow or red-tailed shark | 4-6 in (15 cm) | Territorial and aggressive |
Conclusion
Best fish for a 10-gallon or 20-litre tank should be small, peaceful species that grow under 2 inches. Always start with a cycled tank and introduce fish in batches to set the beneficial bacteria in the aquarium tank.
