Neon Tetra community
- 6 × Neon Tetra
- 6 × Bronze Cory
- 1 × Betta
- 6 × Cardinal Tetra
- 10 × Cherry Shrimp
75% stockedOpen in builder
Tank size guide
40Gallon Tank: Stocking Ideas, Heater & Filter Size
The 40 breeder's wide footprint gives bottom dwellers and territorial fish lots of floor space.
- Dimensions
- 36" × 18" × 16"
- Volume
- 40 gal · 151 L
- Heater
- 120-200 W
- Filter flow
- 160-240 GPH
- Filled weight
- ~400 lb
- Gravel (2" bed)
- ~75 lb
- Weekly water change
- 10 gal (25%)
- Water weight
- 334 lb
40 gallon stocking ideas
Each plan passes the Tank Builder's compatibility check with no conflicts and room to spare. Open one to tweak it.
Zebra Danio community
- 6 × Zebra Danio
- 6 × Panda Cory
- 3 × Guppy
- 8 × Harlequin Rasbora
- 3 × Amano Shrimp
79% stockedOpen in builder
Ember Tetra community
- 8 × Ember Tetra
- 6 × Adolfo's Cory
- 3 × Platy
- 6 × Otocinclus
- 1 × Nerite Snail
71% stockedOpen in builder
Try it yourself
Build your own 40 gallon tank
Pick your tank size, add fish, and instantly see if they get along, how full the tank is, and the heater and filter you need.
Your fish will swim here
40 gal · 151 L
1. Tank size
gal
2. Add fish
Start with the fish you want most
Search above or tap the box for popular picks. Schooling fish come in at their minimum group size.
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Compatibility, stocking level, heater and filter sizes, and the water each fish likes all show up here as you build.
Fish that fit a 40 gallon tank
Popular freshwater species whose recommended minimum is 40 gallons or less. Check they get along in the builder before you buy.
- Neon Tetra1.5" · 10+ gal · groups of 6+
- Green Neon Tetra1" · 10+ gal · groups of 8+
- Cardinal Tetra2" · 15+ gal · groups of 6+
- Betta2.8" · 5+ gal
- Crowntail Betta2.8" · 5+ gal
- Halfmoon Betta2.8" · 5+ gal
- Peaceful Betta2" · 10+ gal
- Plakat Betta2.8" · 5+ gal
- Guppy2.4" · 10+ gal · groups of 3+
- Bronze Cory2.8" · 20+ gal · groups of 6+
- Panda Cory2" · 20+ gal · groups of 6+
- Platy2.5" · 10+ gal · groups of 3+
- Molly4.5" · 20+ gal · groups of 3+
- Sailfin Molly5" · 30+ gal · groups of 3+
- Zebra Danio2" · 10+ gal · groups of 6+
- Harlequin Rasbora1.8" · 15+ gal · groups of 8+
- Ember Tetra0.8" · 10+ gal · groups of 8+
- Cherry Shrimp1.5" · 5+ gal · groups of 10+
- Otocinclus1.6" · 10+ gal · groups of 6+
- Bristlenose Pleco5" · 30+ gal
- Albino Bristlenose Pleco5" · 30+ gal
- Honey Gourami2" · 10+ gal
- Dwarf Gourami3.5" · 15+ gal
- Pearl Gourami4.5" · 30+ gal
Popular fish that need more than 40 gallons
40 gallon tank FAQ
How many fish can go in a 40 gallon tank?
It depends on the fish, not a fixed number. A good example for a 40 gallon is 6 Neon Tetra, 6 Bronze Cory, 1 Betta, 6 Cardinal Tetra, 10 Cherry Shrimp, which comes to about 75% of a cautious stocking limit. Small, tidy fish like tetras and rasboras let you keep more; messy fish like goldfish and plecos fill a tank much faster.
What size heater do I need for a 40 gallon tank?
A 120 to 200 watt heater. Go toward 200 W if the room runs cool.
What size filter does a 40 gallon tank need?
Look for 160 to 240 gallons per hour of flow. For messy fish or a busy tank, go up to about 320 GPH.
What are the dimensions of a 40 gallon tank?
A standard 40 gallon is about 36" long, 18" wide and 16" tall. Another common version is the 40 breeder. A 40 long is 48" x 12" x 16". Brands vary slightly, so measure before buying a stand or lid.
How much does a 40 gallon tank weigh?
The water alone weighs about 334 lb. With glass, gravel and decor, plan on roughly 400 lb, so use a stand made for aquariums.