40 gallon breeder fish tank: dimensions, weight & setup
A standard 40 gallon breeder tank measures 36 × 18 × 16 inches, holds about 39.7 gallons of real water and weighs roughly 435 lb once set up. It is a great size for aquascapes, fancy goldfish, dwarf cichlids and sump-filtered set-ups.
40 Gallon Breeder tank dimensions
| Inches | Centimeters | |
|---|---|---|
| Length | 36 in | 91.4 cm |
| Width (front to back) | 18 in | 45.7 cm |
| Height | 16 in | 40.6 cm |
| Footprint | 648 in² (4.5 ft²) | 4,181 cm² |
| Typical glass | 1/4 in | 6 mm |
These are typical outside dimensions for US glass tanks; brands vary slightly, so measure yours before buying a stand, lid or background.
How much water does it really hold?
| US gallons | Liters | |
|---|---|---|
| Outside dimensions | 44.9 | 169.9 |
| Filled 1 in below the rim | 39.7 | 150.2 |
| With 2 in of gravel | 34.3 | 129.8 |
Dose medication and fertilizer for the real water — about 34 gallons once the tank is aquascaped, not 45.
How much does a 40 gallon breeder tank weigh?
| Empty (estimated, 1/4 in glass) | 59 lb | 27 kg |
|---|---|---|
| Filled with fresh water | 390 lb | 177 kg |
| Set up, fresh water + 2 in gravel | 433 lb | 196 kg |
| Set up as saltwater | 440 lb | 200 kg |
| Floor load under the stand | 96 lb/ft² | 4.6 kPa |
Add rock, decor and the stand (often 40–120 lb). A floor load of 96 lb/ft² is 2.4× the 40 lb/ft² a typical home floor is designed for when averaged over a room, so place the stand across the joists and near a load-bearing wall. Use the weight calculator to include your own rock and stand.
Heater size
| Room temperature (water at 78 °F) | Heater |
|---|---|
| 73 °F (5 °F lift) | 75 W |
| 68 °F (10 °F lift) | 150 W |
| 63 °F (15 °F lift) | 200 W |
Colder room, nano heater or dual-heater setup? See the 40 gallon heater size chart.
Plan maintenance with the water change schedule: a 30% change on this tank is about 10.3 gallons.
Filter flow
| Tank type | Real flow | Filter rating |
|---|---|---|
| Community tropical | 159–238 GPH | 227–340 GPH |
| Planted tank | 198–317 GPH | 283–453 GPH |
| Goldfish, cichlids or heavy feeders | 317–397 GPH | 453–567 GPH |
Substrate
| Depth | Gravel | Sand |
|---|---|---|
| 1 in (2.5 cm) | 36 lb | 35 lb |
| 2 in (5.1 cm) | 72 lb | 70 lb |
| 3 in (7.6 cm) | 108 lb | 104 lb |
Stocking ideas
- 2 fancy goldfish (species-only, with strong filtration)
- 1 pearl gourami + 12 rummy-nose tetras + 6 corydoras + 1 bristlenose pleco
- 1 pair of kribensis + 10 cherry barbs + 6 corydoras
Check any combination — including temperature and group size — in the stocking calculator.
Setup tips
- The 18-inch depth gives room for foreground, midground and background planting — a favorite for aquascapes.
- At 16 inches tall it is easy to reach and light, yet holds about 40 gallons of real water.
- Its footprint fits a 36-inch stand; it is also a common sump size for larger tanks.
FAQ
What are the dimensions of a 40 gallon breeder fish tank?
A standard 40 gallon breeder glass tank measures 36 × 18 × 16 inches (91.4 × 45.7 × 40.6 cm) on the outside, a footprint of 4.5 square feet. Brands differ by up to about half an inch.
How much does a 40 gallon breeder fish tank weigh?
About 60 lb empty, 390 lb filled with water and roughly 435 lb set up with 2 inches of gravel, before rock, decor and the stand.
How many gallons does a 40 gallon breeder tank really hold?
44.9 gallons by its outside dimensions, about 39.7 gallons (150 liters) filled an inch below the rim, and about 34.3 gallons with 2 inches of gravel.
What size heater does a 40 gallon breeder tank need?
150 W to hold 78 °F in a 68 °F room; 75 W in a 73 °F room and 200 W in a 63 °F room.
How much gravel or sand for a 40 gallon breeder tank?
About 36 lb of gravel per inch of depth: 72 lb for a 2-inch bed, or 70 lb of sand.
What filter flow does a 40 gallon breeder tank need?
159–238 GPH of real flow for a community tank (4–6× turnover), so choose a filter rated about 227–340 GPH.