What is a 20 gallon high tank good for?
The 20 gallon high is two feet long and taller than it is deep. It is a fine first community tank for small schooling fish. For bottom dwellers such as corydoras, the 20 long has more floor.
How much water does it really hold?
The label says 20 gallons (76 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 20 gallon high tank holds about 17 gallons (64 liters). Use that smaller number when you dose medicine or water conditioner. Work out your exact water volume
How much does a 20 gallon high tank weigh?
An empty glass 20 gallon high tank weighs about 25 lb (11 kg). Filled, with gravel and a few rocks, it weighs about 205 lb (95 kg). That is as much as an adult person, so put it on a sturdy, level surface. The load on the floor under the tank is about 102 lb per square foot (500 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) | 50 W |
| Normal room, 68 °F (20 °C) | 100 W |
| Cold room, 63 °F (17 °C) | 150 W |
Check your own room and target temperature
What size filter does it need?
For a community tank, look for a filter rated at 70–100 GPH (250–400 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) | 16 lb7 kg | 17 lb8 kg |
| 2 in (5 cm) | 31 lb14 kg | 33 lb15 kg |
| 3 in (7.5 cm) | 47 lb21 kg | 50 lb23 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 4.3 gallons (16 liters) for this tank. A big clean-up change is half: about 8.5 gallons (32 liters). Plan changes from your nitrate reading
How many fish can go in a 20 gallon high 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 16 | 6 |
| Guppy | up to 9 | 3 |
| Harlequin rasbora | up to 12 | 6 |
| Platy | up to 7 | 3 |
| Panda corydoras | up to 11 | 6 |
| Honey gourami | up to 2 | 1 |
| Bronze corydoras | up to 7 | 6 |
| Zebra danio | up to 11 | 6 |
| Cherry barb | up to 11 | 6 |
| German blue ram | 2 | 2 |
Stocking ideas that work
Classic small community: 8 neon tetras, 8 pygmy corydoras, 1 honey gourami. Stocking level 80%. Fish for every level: the tetras in the middle, the gourami at the top, the pygmy corydoras on the bottom.
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 20 gallon high tank?
A standard 20 gallon high glass tank is 24 × 12 × 16 inches (61 × 30 × 41 cm), measured on the outside as length × width × height. Brands differ by up to half an inch.
How much does a 20 gallon high tank weigh?
Empty, about 25 lb (11 kg). Filled with water, gravel and rocks, about 205 lb (95 kg). Add the weight of the stand to find the load on your floor.
What size heater does a 20 gallon high tank need?
In a normal room at 68 °F (20 °C), 100 W holds 78 °F (25.5 °C). In a cold room use 150 W; in a warm room 50 W is enough.
How many fish can I put in a 20 gallon high tank?
It depends on the fish, not just the gallons. As the only kind in the tank, a 20 gallon high tank carries about 16 neon tetras, or 9 guppies, or 12 harlequin rasboras. Mixed tanks hold fewer of each.
How many liters is a 20 gallon high tank?
20 US gallons is 76 liters. Once set up with gravel and decor, the tank holds about 64 liters (17 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