AquariumStocking ideas · checked against sources
What fish can go in a 40 gallon breeder tank?
A standard 40 gallon breeder tank is 36 × 18 × 16 inches. Of the 106 species in our database, 73 fit comfortably and 4 are a tight fit, based on each species' sourced minimum tank size and group size.
Stocking combinations that pass every check
Each set was run through the tank builder's rules: tank size, temperature, pH, hardness, predation, fin-nipping, temperament and stocking level. Treat them as starting points, not prescriptions.
Stocking about 55% · shared temperature 77–81°F
Open in tank builderStocking about 65% · shared temperature 75–81°F
Open in tank builderStocking about 59% · shared temperature 75–81°F
Open in tank builderFish that fit a 40 gallon breeder tank
Tetras & rasboras (22)
- Neon Tetra1.4 in adult · group 8+
- Cardinal Tetra1.7 in adult · group 8+
- Harlequin Rasbora2.1 in adult · group 8+
- Ember Tetra0.9 in adult · group 8+
- Chili Rasbora0.9 in adult · group 8+
- Celestial Pearl Danio1 in adult · group 20+
- Rummy-nose Tetra2.4 in adult · group 10+
- Black Neon Tetra1.7 in adult · group 8+
- Glowlight Tetra1.9 in adult · group 6+
- Lemon Tetra1.9 in adult · group 8+
- Zebra DanioNeeds care2.4 in adult · group 8+
- White Cloud Mountain MinnowNeeds care1.9 in adult · group 10+
- Black Skirt Tetra3.5 in adult · group 12+
- Bleeding Heart Tetra2.9 in adult · group 8+
- Diamond Tetra2.8 in adult · group 6+
- Head-and-tail-light Tetra2.1 in adult · group 6+
- Lambchop Rasbora1.4 in adult · group 8+
- Pearl Danio2.6 in adult · group 8+
- Penguin Tetra1.7 in adult · group 6+
- Pristella Tetra2.1 in adult · group 6+
- Serpae TetraNeeds care1.9 in adult · group 12+
- Silver Tip Tetra2.4 in adult · group 6+
Livebearers (5)
- Guppy2.8 in adult · group 6+
- Platy2.4 in adult · group 6+
- Endler's LivebearerNeeds care1.2 in adult · group 6+
- MollyNeeds care3.8 in adult · group 6+
- Variatus Platy2.4 in adult
Barbs (4)
- Cherry Barb2.4 in adult · group 6+
- Tiger BarbNeeds care2.8 in adult · group 8+
- Gold Barb3.5 in adult · group 8+
- Odessa Barb2.2 in adult · group 8+
Gouramis & bettas (8)
- Honey Gourami2.6 in adult · group 4+
- Dwarf GouramiNeeds care4.2 in adult
- Pearl Gourami5.7 in adult
- BettaNeeds care3.3 in adult
- Moonlight Gourami7.1 in adult
- Paradise FishNeeds care3.8 in adult
- Sparkling Gourami1.9 in adult · group 2+
- Three-spot GouramiNeeds care7.1 in adult
Cichlids (3)
Catfish & plecos (11)
- Bronze Cory3.5 in adult · group 6+
- Panda Cory2.4 in adult · group 6+
- Pygmy Cory1.4 in adult · group 6+
- Julii Cory2.6 in adult · group 6+
- Sterbai Cory3.2 in adult · group 6+
- Bristlenose Pleco5.9 in adult
- OtocinclusNeeds care1.7 in adult · group 6+
- Clown Pleco4.2 in adult
- Glass Catfish3.1 in adult · group 6+
- Peppered CoryNeeds care3.3 in adult · group 6+
- Upside-down Catfish4.7 in adult · group 3+
Loaches (2)
Shrimp & snails (11)
- Cherry Shrimp1.6 in adult · group 10+
- Amano Shrimp2 in adult · group 6+
- Nerite Snail1 in adult
- Mystery Snail2 in adult
- Assassin Snail1.3 in adult
- Bamboo Shrimp4 in adult · group 6+
- Crystal Red Shrimp1.5 in adult
- Ghost Shrimp2 in adult · group 6+
- Japanese Trapdoor Snail2.6 in adult
- Malaysian Trumpet Snail3.1 in adult
- Ramshorn Snail1.2 in adult
Others (7)
- African Dwarf Frog1.4 in adult · group 2+
- Bumblebee GobyNeeds care1.7 in adult · group 6+
- Clown Killifish1.6 in adult · group 8+
- Dwarf Neon Rainbowfish3.8 in adult · group 6+
- Forktail Blue-eye2.8 in adult · group 8+
- Marbled Hatchetfish1.7 in adult · group 10+
- Pea Puffer1.4 in adult
Tight fit (just under a sourced minimum)
Popular fish that outgrow it
- Bolivian RamNeeds 36 in long / 48 gal
- AngelfishNeeds careNeeds 39 in long / 53 gal
- SwordtailNeeds careNeeds 47 in long / 29 gal
- Boesemani RainbowfishNeeds 48 in long / 29 gal
- Bala SharkOutgrows tanksNeeds 96 in long / 228 gal
- Blood Parrot CichlidOutgrows tanksNeeds 55 gal
- Chinese Algae EaterOutgrows tanksNeeds 60 in long / 80 gal
- Clown LoachOutgrows tanksNeeds 72 in long / 170 gal
- Common / Comet GoldfishOutgrows tanksNeeds 39 in long / 42 gal
- Common PlecoOutgrows tanksNeeds 71 in long
- Denison BarbOutgrows tanksNeeds 47 in long / 64 gal
- DiscusNeeds careNeeds 47 in long / 67 gal
Gear sized for 40 gallon breeder
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Common questions
How many fish can go in a 40 gallon breeder tank?
It depends on adult size and waste output, not inches per gallon. The combinations on this page stay under about 80% of a sensible load for 40 gallons in our estimate.
What fish outgrow a 40 gallon breeder tank?
Popular examples include Bolivian Ram, Angelfish, Swordtail, Boesemani Rainbowfish, Bala Shark, Blood Parrot Cichlid.
What heater size does a 40 gallon breeder tank need?
About 200 W, using roughly 5 watts per gallon.