40-Gallon Tank Setup: What to Buy and What Fits
A 40-gallon breeder is wide and shallow, which gives fish more floor and swimming space than its volume suggests. It handles big schools, active barbs and several centerpiece fish.
- Dimensions
- 36 × 18 × 16 inlength × width × height
- Weight when full
- ~458 lbswater, substrate, gear
- Heater
- 150 wattsfor 77°F in a 68°F room
- Substrate
- 60 lbsfor a 1.5 inch layer
3 stocking ideas for a 40-gallon tank
Each one passes our checks for tank size, group size, temperature and temperament. Open one in the builder to adjust it.
Warm-water community
Cardinals, corydoras and a pearl gourami.
- 12 × Cardinal tetra
- 8 × Corydoras catfish
- 1 × Pearl gourami
- 1 × Bristlenose pleco
Active barb tank
Fast, bold fish that keep to themselves.
- 6 × Tiger barb
- 6 × Zebra danio
- 1 × Bristlenose pleco
Fancy goldfish trio
Three goldfish with room to grow.
- 3 × Fancy goldfish
Shopping list for a 40-gallon tank
Sized for the “Warm-water community” idea above. Change the fish in the builder and the list updates.
40-gallon tank
- These fit a 40-gallon tank and get along. Aim for about 77°F.
Equipment, sized for this tank
Starter supplies
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Fish that fit a 40-gallon tank
The most of each you could keep if it were the only species in the tank.
| Fish | Kept alone, up to | Group size | Temperature |
|---|---|---|---|
| Betta | 1 | One per tank | 76–82°F |
| Neon tetra | 40 | 6 or more | 70–79°F |
| Cardinal tetra | 40 | 6 or more | 75–82°F |
| Ember tetra | 90 | 6 or more | 73–82°F |
| Rummy-nose tetra | 30 | 6 or more | 75–81°F |
| Black skirt tetra | 20 | 6 or more | 70–79°F |
| Guppy | 30 | 3 or more | 72–82°F |
| Endler's livebearer | 51 | 3 or more | 72–82°F |
| Platy | 20 | 3 or more | 70–80°F |
| Molly | 10 | 3 or more | 75–80°F |
| Swordtail | 9 | 3 or more | 72–79°F |
| Zebra danio | 30 | 6 or more | 64–77°F |
| White cloud minnow | 45 | 6 or more | 60–72°F |
| Harlequin rasbora | 32 | 6 or more | 73–82°F |
| Chili rasbora | 120 | 6 or more | 72–82°F |
| Cherry barb | 27 | 6 or more | 73–81°F |
| Tiger barb | 15 | 6 or more | 72–79°F |
| Corydoras catfish | 27 | 6 or more | 72–79°F |
| Pygmy corydoras | 72 | 6 or more | 72–79°F |
| Bristlenose pleco | 6 | One or more | 73–81°F |
| Otocinclus | 40 | 6 or more | 72–79°F |
| Kuhli loach | 30 | 5 or more | 75–82°F |
| Dwarf gourami | 1 | One per tank | 72–82°F |
| Honey gourami | 20 | One or more | 72–82°F |
| Pearl gourami | 8 | One or more | 75–82°F |
| Angelfish | 4 | One or more | 76–82°F |
| German blue ram | 14 | One or more | 78–85°F |
| Fancy goldfish | 2 | One or more | 60–74°F |
| Cherry shrimp | 160 | 5 or more | 65–80°F |
| Amano shrimp | 120 | 3 or more | 68–80°F |
| Nerite snail | 90 | One or more | 72–80°F |
| Mystery snail | 24 | One or more | 68–82°F |
40-gallon tank questions
How many fish can I put in a 40-gallon tank?
It depends on the fish. As examples, a 40-gallon tank comfortably holds 1 betta, or 40 neon tetras, or 30 guppies if kept alone. Mixed tanks hold fewer of each. The builder shows the stocking level for any combination.
What size heater does a 40-gallon tank need?
About 150 watts to hold 77°F in a 68°F room. A colder room or warmer target needs more.
What size filter does a 40-gallon tank need?
Look for a filter rated for at least 240 gallons per hour, which turns the tank over about 6 times an hour. Go higher for messy fish such as goldfish or plecos.
How much does a 40-gallon tank weigh?
About 458 pounds when filled with water, substrate and equipment. Standard dimensions are 36 × 18 × 16 inches.