How many fish in a 125 gallon tank?
A 125 US gal (473 L) tank is usually 72 in (183 cm) long. By size, 49 of the 53 species in this reference fit it. The table shows how many of each the tank can carry if kept on their own, at under 80% of its bioload.
A mix shares the same capacity, so three species at a third each is the limit, not three full rows. Check a mix with the planner; it also weighs water and temperament.
Species that fit a 125 gallon tank
| Species | Adult size | Up to, kept alone | Group |
|---|---|---|---|
| Black neon tetra | 1.4 in (3.5 cm) | 172 | 10+ |
| Black skirt tetra | 3 in (7.5 cm) | 44 | 12+ |
| Cardinal tetra | 1.4 in (3.5 cm) | 172 | 10+ |
| Congo tetra | 3.1 in (8 cm) | 46 | |
| Ember tetra | 0.8 in (2 cm) | 269 | 10+ |
| Glowlight tetra | 1.6 in (4 cm) | 146 | 6+ |
| Lemon tetra | 1.6 in (4 cm) | 130 | 10+ |
| Neon tetra | 1.2 in (3 cm) | 202 | 10+ |
| Rummy-nose tetra | 2 in (5 cm) | 106 | 10+ |
| Serpae tetra | 1.6 in (4 cm) | 130 | 12+ |
| Endler's livebearer | 1 in (2.5 cm) | 235 | |
| Guppy | 2.4 in (6 cm) | 78 | |
| Molly | 3.1 in (8 cm) | 37 | |
| Platy | 2 in (5 cm) | 88 | |
| Swordtail | 5.5 in (14 cm) | 14 | |
| Celestial pearl danio | 0.8 in (2.1 cm) | 278 | |
| Chili rasbora | 1.4 in (3.5 cm) | 195 | 10+ |
| Harlequin rasbora | 2 in (5 cm) | 106 | 10+ |
| White cloud mountain minnow | 1.6 in (4 cm) | 169 | 10+ |
| Zebra danio | 2 in (5 cm) | 127 | 10+ |
| Cherry barb | 2 in (5 cm) | 106 | 10+ |
| Rosy barb | 5.5 in (14 cm) | 12 | 10+ |
| Tiger barb | 2.8 in (7 cm) | 50 | 10+ |
| Bristlenose pleco | 6 in (15 cm) | 9 | |
| Bronze corydoras | 3 in (7.5 cm) | 42 | 6+ |
| Glass catfish | 2.6 in (6.5 cm) | 84 | 6+ |
| Otocinclus | 2 in (5 cm) | 106 | 6+ |
| Panda corydoras | 2 in (5 cm) | 88 | 6+ |
| Peppered corydoras | 2.8 in (7 cm) | 48 | 5+ |
| Pygmy corydoras | 1.2 in (3 cm) | 202 | 6+ |
| Kuhli loach | 4.7 in (12 cm) | 51 | 6+ |
| Yoyo loach | 6.3 in (16 cm) | 10 | 6+ |
| Betta | 2.8 in (7 cm) | 59 | |
| Dwarf gourami | 3.7 in (9.5 cm) | 27 | |
| Honey gourami | 5.4 in (14 cm) | 12 | 6+ |
| Paradise fish | 3.1 in (8 cm) | 46 | |
| Pearl gourami | 4.7 in (12 cm) | 16 | |
| Angelfish | 5.9 in (15 cm) | 9 | |
| Cockatoo dwarf cichlid | 3 in (7.5 cm) | 44 | |
| Convict cichlid | 5.9 in (15 cm) | 10 | |
| Discus | 5.5 in (14 cm) | 10 | |
| German blue ram | 1.7 in (4.2 cm) | 121 | |
| Kribensis | 4.3 in (11 cm) | 20 | |
| Boeseman's rainbowfish | 4.3 in (11 cm) | 20 | 8+ |
| Red tail shark | 5.1 in (13 cm) | 17 | |
| Siamese algae eater | 6.3 in (16 cm) | 14 | |
| Cherry shrimp | 1.6 in (4 cm) | 213 | |
| Mystery snail | 2 in (5 cm) | 112 | |
| Nerite snail | 1.5 in (3.8 cm) | 163 |
Too big for a 125 gallon tank
- Common plecoNeeds 284 L (75 US gal), and grows to 58 cm (23 in).
- Clown loachNeeds 648 L (171 US gal), at least 180 cm (71 in) long.
- OscarNeeds 540 L (143 US gal), at least 150 cm (59 in) long.
- GoldfishNeeds 76 L (20 US gal), and grows to 48 cm (19 in).
A guide, not a guarantee. Tank sizes: 5 gal, 10 gal, 20 gal, 29 gal, 40 gal, 55 gal, 75 gal.