What is a 5 gallon tank good for?
A 5 gallon tank (sold as 5.5 gallons) is the smallest tank we would put a fish in. It suits one betta, or a colony of shrimp. It is not big enough for a school of fish.
How much water does it really hold?
The label says 5.5 gallons (21 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 5 gallon tank holds about 4.7 gallons (18 liters). Use that smaller number when you dose medicine or water conditioner. Work out your exact water volume
How much does a 5 gallon tank weigh?
An empty glass 5 gallon tank weighs about 8 lb (4 kg). Filled, with gravel and a few rocks, it weighs about 60 lb (30 kg). 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 70 lb per square foot (340 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) | 25 W |
| Normal room, 68 °F (20 °C) | 25 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 20–30 GPH (50–100 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) | 7 lb4 kg | 8 lb4 kg |
| 2 in (5 cm) | 14 lb7 kg | 15 lb7 kg |
| 3 in (7.5 cm) | 21 lb10 kg | 22 lb10 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 1.2 gallons (4 liters) for this tank. A big clean-up change is half: about 2.3 gallons (9 liters). Plan changes from your nitrate reading
How many fish can go in a 5 gallon 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 28 | 6 |
| Chili rasbora | 8 | 8 |
Build your own fish list for this tank
Questions and answers
What are the dimensions of a 5 gallon tank?
A standard 5 gallon glass tank is 16 × 8 × 10 inches (41 × 20 × 25 cm), measured on the outside as length × width × height. Brands differ by up to half an inch.
How much does a 5 gallon tank weigh?
Empty, about 8 lb (4 kg). Filled with water, gravel and rocks, about 60 lb (30 kg). Add the weight of the stand to find the load on your floor.
What size heater does a 5 gallon tank need?
In a normal room at 68 °F (20 °C), 25 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 5 gallon tank?
It depends on the fish, not just the gallons. As the only kind in the tank, a 5 gallon tank carries about 1 betta, or 28 cherry shrimp, or 8 chili rasboras. Mixed tanks hold fewer of each.
How many liters is a 5 gallon tank?
5.5 US gallons is 21 liters. Once set up with gravel and decor, the tank holds about 18 liters (5 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