Neon Tetra community
- 6 × Neon Tetra
- 6 × Panda Cory
- 1 × Honey Gourami
- 1 × Nerite Snail
78% stockedOpen in builder
Tank size guide
20Gallon Tank: Stocking Ideas, Heater & Filter Size
The size most people wish they had started with. Enough water to stay stable and room for a real community.
- Dimensions
- 24" × 12" × 16"
- Volume
- 20 gal · 76 L
- Heater
- 60-100 W
- Filter flow
- 80-120 GPH
- Filled weight
- ~200 lb
- Gravel (2" bed)
- ~33 lb
- Weekly water change
- 5 gal (25%)
- Water weight
- 167 lb
20 gallon stocking ideas
Each plan passes the Tank Builder's compatibility check with no conflicts and room to spare. Open one to tweak it.
Cardinal Tetra community
- 6 × Cardinal Tetra
- 1 × Kribensis
- 1 × Betta
- 3 × Amano Shrimp
77% stockedOpen in builder
Zebra Danio community
- 6 × Zebra Danio
- 1 × African Butterfly Cichlid
- 3 × Guppy
- 1 × Mystery Snail
76% stockedOpen in builder
Try it yourself
Build your own 20 gallon tank
Pick your tank size, add fish, and instantly see if they get along, how full the tank is, and the heater and filter you need.
Your fish will swim here
20 gal · 76 L
1. Tank size
gal
2. Add fish
Start with the fish you want most
Search above or tap the box for popular picks. Schooling fish come in at their minimum group size.
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Compatibility, stocking level, heater and filter sizes, and the water each fish likes all show up here as you build.
Fish that fit a 20 gallon tank
Popular freshwater species whose recommended minimum is 20 gallons or less. Check they get along in the builder before you buy.
- Neon Tetra1.5" · 10+ gal · groups of 6+
- Green Neon Tetra1" · 10+ gal · groups of 8+
- Cardinal Tetra2" · 15+ gal · groups of 6+
- Betta2.8" · 5+ gal
- Crowntail Betta2.8" · 5+ gal
- Halfmoon Betta2.8" · 5+ gal
- Peaceful Betta2" · 10+ gal
- Plakat Betta2.8" · 5+ gal
- Guppy2.4" · 10+ gal · groups of 3+
- Bronze Cory2.8" · 20+ gal · groups of 6+
- Panda Cory2" · 20+ gal · groups of 6+
- Platy2.5" · 10+ gal · groups of 3+
- Molly4.5" · 20+ gal · groups of 3+
- Zebra Danio2" · 10+ gal · groups of 6+
- Harlequin Rasbora1.8" · 15+ gal · groups of 8+
- Ember Tetra0.8" · 10+ gal · groups of 8+
- Cherry Shrimp1.5" · 5+ gal · groups of 10+
- Otocinclus1.6" · 10+ gal · groups of 6+
- Honey Gourami2" · 10+ gal
- Dwarf Gourami3.5" · 15+ gal
- Kuhli Loach4" · 20+ gal · groups of 5+
- German Blue Ram2.5" · 20+ gal
- Cherry Barb2" · 15+ gal · groups of 6+
- White Cloud Mountain Minnow1.5" · 10+ gal · groups of 6+
Popular fish that need more than 20 gallons
20 gallon tank FAQ
How many fish can go in a 20 gallon tank?
It depends on the fish, not a fixed number. A good example for a 20 gallon is 6 Neon Tetra, 6 Panda Cory, 1 Honey Gourami, 1 Nerite Snail, which comes to about 78% of a cautious stocking limit. Small, tidy fish like tetras and rasboras let you keep more; messy fish like goldfish and plecos fill a tank much faster.
What size heater do I need for a 20 gallon tank?
A 60 to 100 watt heater. Go toward 100 W if the room runs cool.
What size filter does a 20 gallon tank need?
Look for 80 to 120 gallons per hour of flow. For messy fish or a busy tank, go up to about 160 GPH.
What are the dimensions of a 20 gallon tank?
A standard 20 gallon is about 24" long, 12" wide and 16" tall. Another common version is the 20 long: 30" x 12" x 12", which gives fish more swimming length. Brands vary slightly, so measure before buying a stand or lid.
How much does a 20 gallon tank weigh?
The water alone weighs about 167 lb. With glass, gravel and decor, plan on roughly 200 lb, so use a stand made for aquariums.