What is a 40 gallon breeder tank good for?
The 40 breeder is a favorite of experienced keepers. Its big, low footprint gives fish lots of floor and makes planting and cleaning easy. It suits a pair of fancy goldfish, a colony of shell dwellers, or a lively community.
How much water does it really hold?
The label says 40 gallons (151 liters). That is the tank filled to the very brim, measured from outside the glass. In real life the glass, the gap at the top, the gravel and the decor take up room. A set-up 40 gallon breeder tank holds about 34 gallons (129 liters). Use that smaller number when you dose medicine or water conditioner. Work out your exact water volume
How much does a 40 gallon breeder tank weigh?
An empty glass 40 gallon breeder tank weighs about 40 lb (19 kg). Filled, with gravel and a few rocks, it weighs about 405 lb (185 kg). That is as much as two or three adults, so use a stand made for aquariums, not ordinary furniture. The load on the floor under the tank is about 90 lb per square foot (440 kg/m²). Add your own stand and rocks
What size heater does it need?
The colder your room, the bigger the heater. These sizes hold the water at 78 °F (25.5 °C), right for most tropical fish.
| Your room | Heater to buy |
|---|---|
| Warm room, 73 °F (23 °C) | 100 W |
| Normal room, 68 °F (20 °C) | 200 W |
| Cold room, 63 °F (17 °C) | 300 W |
Check your own room and target temperature
What size filter does it need?
For a community tank, look for a filter rated at 140–200 GPH (500–750 L/h). That moves all the water through the filter four to six times an hour. Goldfish and big cichlids need more. Size a filter for your kind of tank
How much gravel or sand?
| Depth | Gravel | Sand |
|---|---|---|
| 1 in (2.5 cm) | 35 lb16 kg | 37 lb17 kg |
| 2 in (5 cm) | 70 lb32 kg | 74 lb34 kg |
| 3 in (7.5 cm) | 104 lb48 kg | 111 lb51 kg |
Two inches suits most tanks. Rooted plants like three. Work it out in bags
How much water to change
A normal weekly water change is a quarter of the water: about 8.5 gallons (32 liters) for this tank. A big clean-up change is half: about 17 gallons (64 liters). Plan changes from your nitrate reading
How many fish can go in a 40 gallon breeder tank?
It depends on which fish. The table shows how many of each the tank carries comfortably if that fish is the only kind in the tank. If you mix kinds, keep fewer of each.
| Fish | How many | Keep at least |
|---|---|---|
| Neon tetra | up to 32 | 6 |
| Guppy | up to 18 | 3 |
| Bronze corydoras | up to 14 | 6 |
| Molly | up to 6 | 3 |
| Tiger barb | up to 13 | 8 |
| Pearl gourami | up to 2 | 1 |
| Bristlenose pleco | up to 2 | 1 |
| Dwarf neon rainbowfish | up to 15 | 6 |
| Fancy goldfish | 1 | 1 |
| Yellow lab | up to 6 | 4 |
Build your own fish list for this tank
Fish that need a bigger tank
These fish are often sold for tanks this size, but they outgrow it:
- Common goldfish: grows to 12 in (30 cm) and needs at least 75 gallons (284 liters).
- Oscar: grows to 12 in (30 cm) and needs at least 75 gallons (284 liters).
- Common pleco: grows to 16 in (40 cm) and needs at least 150 gallons (570 liters).
- Bala shark: grows to 14 in (35 cm) and needs at least 150 gallons (570 liters).
Questions and answers
What are the dimensions of a 40 gallon breeder tank?
A standard 40 gallon breeder glass tank is 36 × 18 × 16 inches (91 × 46 × 41 cm), measured on the outside as length × width × height. Brands differ by up to half an inch.
How much does a 40 gallon breeder tank weigh?
Empty, about 40 lb (19 kg). Filled with water, gravel and rocks, about 405 lb (185 kg). Add the weight of the stand to find the load on your floor.
What size heater does a 40 gallon breeder tank need?
In a normal room at 68 °F (20 °C), 200 W holds 78 °F (25.5 °C). In a cold room use 300 W; in a warm room 100 W is enough.
How many fish can I put in a 40 gallon breeder tank?
It depends on the fish, not just the gallons. As the only kind in the tank, a 40 gallon breeder tank carries about 32 neon tetras, or 18 guppies, or 14 bronze corydoras. Mixed tanks hold fewer of each.
How many liters is a 40 gallon breeder tank?
40 US gallons is 151 liters. Once set up with gravel and decor, the tank holds about 129 liters (34 gallons) of water.
Other tank sizes
Dimensions are the common North American and European standard sizes; brands differ slightly. Weights assume standard glass of typical thickness, 4 cm of gravel and light rockwork. How we calculate