What is a 40×25×25 cm tank good for?
A 40×25×25 cm tank holds 25 liters, close to a 5.5 gallon tank in American sizes. It is a nano tank. Small tanks change temperature and water quality fast, so stock lightly and test often.
How much water does it really hold?
The label says 25 liters (6.6 US gallons). 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 40×25×25 cm tank holds about 21 liters (5.6 US gallons). Use that smaller number when you dose medicine or water conditioner. Work out your exact water volume
How much does a 40×25×25 cm tank weigh?
An empty glass 40×25×25 cm tank weighs about 4 kg (9 lb). Filled, with gravel and a few rocks, it weighs about 35 kg (75 lb). That is about as much as a small child, so put it on a sturdy, level surface. The load on the floor under the tank is about 330 kg/m² (68 lb per square foot). 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) | 25 W |
| Normal room, 68 °F (20 °C) | 50 W |
| Cold room, 63 °F (17 °C) | 50 W |
Check your own room and target temperature
What size filter does it need?
For a community tank, look for a filter rated at 100–150 L/h (20–30 GPH). 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) | 4 kg9 lb | 4 kg9 lb |
| 2 in (5 cm) | 8 kg17 lb | 8 kg18 lb |
| 3 in (7.5 cm) | 12 kg25 lb | 12 kg27 lb |
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 5 liters (1.4 US gallons) for this tank. A big clean-up change is half: about 11 liters (2.8 US gallons). Plan changes from your nitrate reading
How many fish can go in a 40×25×25 cm 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 |
|---|---|---|
| Betta | 1 | 1 |
| Cherry shrimp | up to 33 | 6 |
| Chili rasbora | up to 9 | 8 |
Build your own fish list for this tank
Questions and answers
How many liters is a 40×25×25 cm aquarium?
A 40×25×25 cm tank is 25 liters brim-full (7 US gallons, 5 UK gallons). Set up, it holds about 21 liters of water.
How much does a 40×25×25 cm tank weigh?
Empty, about 4 kg (9 lb). Filled with water, gravel and rocks, about 35 kg (75 lb). Add the weight of the stand to find the load on your floor.
What size heater does a 40×25×25 cm tank need?
In a normal room at 68 °F (20 °C), 50 W holds 78 °F (25.5 °C). In a cold room use 50 W; in a warm room 25 W is enough.
How many fish can I put in a 40×25×25 cm tank?
It depends on the fish, not just the gallons. As the only kind in the tank, a 40×25×25 cm tank carries about 1 betta, or 33 cherry shrimp, or 9 chili rasboras. Mixed tanks hold fewer of each.
Other tank sizes
Dimensions are the common North American and European standard sizes; brands differ slightly. Weights assume float glass of typical thickness, 4 cm of gravel and light rockwork. How we calculate