Fish tank stocking ideas by tank size

Stocking ideas · 41 setups from 5 to 75 gallons · By Andy · Updated Oct 26, 2026

Not sure what to put in your tank? Pick your size below. Every setup has been checked with the free stocking calculator for space, group sizes, temperature and tankmates, and opens in the calculator with one tap so you can change it.

Pick your tank size

5 gallon stocking ideas
5 setups. A betta, a shrimp colony or a tiny nano school.
10 gallon stocking ideas
6 setups. A betta tank, a small school, guppies or shrimp.
20 gallon stocking ideas
6 setups. Peaceful community tanks, and 20 high vs 20 long.
29 gallon stocking ideas
6 setups. The classic beginner tank, from a neon school to a betta showcase.
40 gallon breeder stocking ideas
6 setups. A wide, deep tank for bottom dwellers and aquascapes.
55 gallon stocking ideas
6 setups. Angelfish, big tetra schools and fancy goldfish.
75 gallon stocking ideas
6 setups. Angelfish groups, big communities and goldfish.

Want every plan in one printable? Stocking Plans by Tank Size has 41 checked setups for 5 to 75 gallon tanks, 32 fish care cards and a plan-your-own worksheet. Get the plans for $7

Not sure how big your tank is?

Measure the inside length, width and height and use the aquarium volume calculator. It also tells you the heater and filter size.

Stocking rules that always apply

Cycle the tank first. See how to cycle a new fish tank.
Add fish a group at a time, a week or two apart, so the good bacteria keep up.
Keep schooling fish in groups of 6 or more.
Match temperatures and don't mix goldfish with tropical fish. See the aquarium temperature guide.
Plan for adult size, not the size in the store.

Build your own

Use the fish finder to see which fish fit your tank, then check the full mix in the stocking calculator. For the facts on every fish in one place, see the freshwater fish care sheets.

Want printable plans? Your First Aquarium includes ready-made stocking plans and care cards for 15 beginner fish. Get the guide for $12