How many fish in a 75 gallon tank?
Short answer: roughly 75 small, slim fish (like neon tetras or rasboras) in a well-filtered 75 gallon tank — far fewer if they grow larger. Good options: Discus.
Tested stocking ideas
Discus and cardinals
5 × Discus, 12 × Cardinal tetra
Species that fit a 75 gallon tank
| Species | How many (alone) | Note |
|---|---|---|
| Angelfish | up to 8 | |
| Betta fish | 1 | one male |
| Bristlenose pleco | up to 10 | |
| Cherry shrimp | up to 99 | groups of 10+ |
| Dwarf gourami | 1 | one male |
| Fancy goldfish | up to 4 | |
| Guppy | up to 60 | groups of 3+ |
| Harlequin rasbora | up to 70 | groups of 6+ |
| Molly | up to 18 | groups of 3+ |
| Neon tetra | up to 99 | groups of 6+ |
| Platy | up to 48 | groups of 3+ |
| Tiger barb | up to 38 | groups of 6+ |
| Amano shrimp | up to 99 | groups of 3+ |
| Black skirt tetra | up to 48 | groups of 6+ |
| Bronze cory | up to 34 | groups of 6+ |
| Cardinal tetra | up to 99 | groups of 6+ |
| Celestial pearl danio | up to 99 | groups of 6+ |
| Cherry barb | up to 70 | groups of 6+ |
| Chili rasbora | up to 99 | groups of 8+ |
| Discus | up to 6 | groups of 5+ |
| Electric yellow cichlid | up to 18 | |
| Ember tetra | up to 99 | groups of 8+ |
| Endler's livebearer | up to 99 | groups of 3+ |
| German blue ram | up to 63 | |
| Glowlight tetra | up to 99 | groups of 6+ |
| Honey gourami | up to 55 | |
| Kribensis | up to 20 | |
| Kuhli loach | up to 37 | groups of 5+ |
| Mystery snail | up to 99 | |
| Nerite snail | up to 99 | |
| Otocinclus | up to 99 | groups of 6+ |
| Panda cory | up to 63 | groups of 6+ |
| Pea puffer | up to 99 | |
| Pearl gourami | up to 14 | |
| Rainbow shark | 1 | one male |
| Red tail shark | 1 | one male |
| Rummy nose tetra | up to 70 | groups of 8+ |
| Serpae tetra | up to 82 | groups of 6+ |
| Siamese algae eater | up to 9 | |
| Swordtail | up to 13 | groups of 3+ |
| Three spot gourami | up to 9 | |
| White cloud mountain minnow | up to 99 | groups of 6+ |
| Zebra danio | up to 70 | groups of 6+ |
| Black neon tetra | up to 99 | groups of 6+ |
| Bloodfin tetra | up to 61 | groups of 6+ |
| Boesemani rainbowfish | up to 16 | groups of 6+ |
| Bolivian ram | up to 28 | |
| Buenos Aires tetra | up to 38 | groups of 6+ |
| Chinese algae eater | 1 | one male |
| Cockatoo dwarf cichlid | up to 31 | |
| Congo tetra | up to 28 | groups of 6+ |
| Convict cichlid | up to 8 | |
| Dwarf neon rainbowfish | up to 31 | groups of 6+ |
| Firemouth cichlid | up to 8 | |
| Forktail blue-eye | up to 60 | groups of 6+ |
| Glass catfish | up to 53 | groups of 6+ |
| Gold barb | up to 34 | groups of 6+ |
| Jack Dempsey | up to 2 | |
| Lemon tetra | up to 70 | groups of 6+ |
| Odessa barb | up to 48 | groups of 6+ |
| Paradise fish | 1 | one male |
| Peppered cory | up to 38 | groups of 6+ |
| Pygmy cory | up to 99 | groups of 8+ |
| Rosy barb | up to 12 | groups of 6+ |
| Sparkling gourami | up to 89 | |
| Sterbai cory | up to 38 | groups of 6+ |
| Upside-down catfish | up to 20 | groups of 3+ |
| X-ray tetra | up to 93 | groups of 6+ |
How we calculate it
We count each fish in "units": one slim 5 cm (2 inch) fish = 1 unit, and a well-filtered tank holds about 1 unit per US gallon. Units scale with (adult length ÷ 5 cm)1.5 × a body-mass factor, so a 15 cm angelfish counts as about 8 units, not 3. Species are excluded if their recommended minimum tank is larger than 75 gallons.
Other sizes: 5 gallon · 10 gallon · 20 gallon · 29 gallon · 40 gallon · 55 gallon
FAQ
How many fish can I put in a 75 gallon tank?
It depends on the species. As a conservative guide, a 75 gallon tank holds about 75 small (2 inch) slim fish, far fewer large or heavy-bodied fish. The table above lists the maximum for each suitable species kept on its own.
Is the 1 inch per gallon rule accurate?
Only for small, slim fish. Waste output grows much faster than length, so a 6 inch fish produces far more waste than three 2 inch fish. We scale by body size and body shape instead.