Guide
Best fish for a 20 gallon tank
Stocking ideas: community fish, schooling species, and how to avoid overstocking.
- 20 gallons suits schooling fish, corydoras, and a centrepiece.
- Stock gradually; test water and do regular water changes.
Why 20 gallons works well
A 20 gallon gives room for a small school of tetras or rasboras, corydoras, and a centrepiece. Water is more stable than in smaller tanks. See how many fish per gallon and overstocking. Try our free stocking calculator.
Stocking ideas
- Six to eight neon tetras, six corydoras, and a dwarf gourami.
- One betta with a small school (see betta tank mates).
- Livebearers: guppies or platies; they breed so plan for offspring.
Keep learning
Stable aquariums come from consistent testing and patient stocking. Continue with our water parameters guide, how to cycle a tank, and combining fish safely. For logging and strip scans, see App-aquatic.
Log parameters, scan strips offline, and run stocking checks with App-aquatic.
Get the free appWhy 20 gallons works well?
A 20 gallon gives room for a small school of tetras or rasboras, corydoras , and a centrepiece. Water is more stable than in smaller tanks. See how many fish per gallon and overstocking . Try our free stocking calculator .
How does regular testing help?
Regular testing lets you catch ammonia, nitrite, and nitrate shifts before fish show stress. Log results over time to see trends, not single snapshots.
Where can I track parameters and strips?
App-aquatic logs water tests, supports offline test strip scanning, species ID, and stocking checks — with reminders so maintenance does not slip.
More guides · 10 gallon · 5 gallon · Community tank · Get the app