20 gallon long fish tank size and measurements
How big is a 20 gallon long tank? It is about 2.5 feet long (30 in), 12 inches from front to back and 12 inches tall, so it needs a stand or space at least 30 x 12 inches.
- Outside dimensions
- 30 x 12 x 12 in76.2 x 30.5 x 30.5 cm
- Volume
- 20 US gal76 L, 17 UK gal
- Footprint
- 2.5 sq ft360 sq in
- Water weight
- 167 lb76 kg
Measured from the outside, these dimensions hold about 18.7 US gallons. Real water volume is lower because of glass thickness, substrate, decor and the gap below the rim. Check the real figure with the aquarium volume calculator.
How much does a 20 gallon long tank weigh?
A 20 gallon long tank weighs about 233 lb (106 kg) once set up, counting the empty glass (25 lb), the water and 2 inches of gravel. Use a stand rated for the full weight, on a level floor. The fish tank weight guide compares every size.
How much gravel or sand for a 20 gallon long tank?
| Bed depth | Gravel | Sand | Aquasoil |
|---|---|---|---|
| 1 in (2.5 cm) | 21 lb | 20 lb | 6 L |
| 2 in (5.1 cm) | 42 lb | 40 lb | 12 L |
| 3 in (7.6 cm) | 62 lb | 59 lb | 18 L |
Based on a 30 x 12 in floor and typical bulk densities.
Different depth? Use the aquarium substrate calculator.
Heater and filter size for a 20 gallon long tank
A common rule is 3–5 watts per gallon, so a 20 gallon long tank needs about 60–100 W: one 100 W heater suits most rooms. Use the higher end in cold rooms.
For filtration, aim to turn the water over 4–6 times an hour: a filter rated around 80–120 gallons per hour.
Fish that suit a 20 gallon long tank
- Corydoras and other bottom dwellers
- Active schooling fish such as zebra danios
- Kuhli loaches
- Shrimp colonies
Starting ideas only. Check each species' adult size, temperament and water needs before buying.
Compare nearby sizes
See every size in the aquarium size chart.
Further reading
Frequently asked questions
What are the dimensions of a 20 gallon long tank?
A standard 20 gallon long aquarium measures about 30 x 12 x 12 inches (76.2 x 30.5 x 30.5 cm), length x width x height. Brands vary by a fraction of an inch.
How long is a 20 gallon long tank?
About 30 inches (76.2 cm), or 2.5 feet.
How big is a 20 gallon long tank?
It is about 2.5 feet long, 12 inches deep and 12 inches tall, and takes up 2.5 square feet of floor.
How much does a 20 gallon long tank weigh when full?
About 233 lb (106 kg) once set up, counting the empty glass (25 lb), the water and 2 inches of gravel.
How much gravel do I need for a 20 gallon long tank?
For a 2 inch bed, about 42 lb of gravel or 40 lb of sand.
What size heater does a 20 gallon long tank need?
About 60–100 watts in total, so one 100 W heater suits most rooms.
Last updated .