Aquarium Stocking Chart by Tank Size
Sensible example stocking lists for 5, 10, 20, 29, 40, 55, and 75 gallon freshwater tanks, with bioload and schooling rules to plan a balanced community.
The most common beginner mistake is too many fish, too soon, in too small a tank. Stocking is about bioload and behavior, not a simple inch-per-gallon shortcut. The example lists below are balanced, beginner-friendly communities for each common tank size. Treat them as proven templates, then fine-tune with the stocking calculator before you buy a single fish.
Quick answer: A 5 gallon suits 1 betta plus a snail, or a shrimp colony. A 10 gallon fits one small school of 6 to 8. A 20 long or 29 gallon supports a real community of 2 to 3 species. A 55 to 75 gallon handles larger schools, a centerpiece pair, or a couple of fancy goldfish. Stock gradually after the tank is fully cycled, and confirm any plan with our stocking calculator.
Stocking chart by tank size
These are sensible, beginner-safe examples, not the absolute maximum. Always cycle the tank first, add fish in small batches, and keep schooling species in groups of six or more.
| Tank size | Example stocking | Notes |
|---|---|---|
| 5 gallon | 1 betta + 1 nerite snail, OR 8 to 10 cherry shrimp + snails | Too small for any schooling fish; low bioload only |
| 10 gallon | 1 betta + 6 pygmy corydoras, OR 8 neon tetras + 1 nerite snail | Room for one small school or one centerpiece, not both |
| 20 gallon long | 8 neon tetras + 6 corydoras + 1 honey gourami | The footprint makes this the best true-beginner community |
| 29 gallon | 10 cardinal tetras + 6 corydoras + 2 honey gouramis + 1 bristlenose pleco | Comfortable multi-species community with a cleanup crew |
| 40 gallon breeder | Pair of angelfish + 12 rummynose tetras + 8 corydoras + 1 bristlenose pleco | Wide footprint suits a centerpiece pair plus large schools |
| 55 gallon | 12 tetras + 8 corydoras + trio of dwarf gouramis + 1 bristlenose, OR 2 fancy goldfish | Choose a tropical community or a goldfish setup, not both |
| 75 gallon | Angelfish group + 15 larger tetras + 10 corydoras + plecos, OR 3 to 4 fancy goldfish | Plenty of room for bigger schools or a small cichlid setup |
Why these lists work
Each example balances three things: total bioload the filter and water changes can handle, schooling needs that keep fish calm and colorful, and a mix of swimming levels so the tank looks full without crowding. Notice how small tanks hold one focal group while larger tanks layer a centerpiece species, a mid-water school, and a bottom cleanup crew. That layering, not raw fish count, is what makes a tank look alive and stay healthy.
Notice too that the same volume can mean different things. A 55 gallon is generous for a tropical community but only enough for two fancy goldfish, because goldfish are large, long-lived, and produce far more waste than slim tetras. Always plan around adult size and waste output rather than the cute juveniles in the store tank.
Tank Kits to Get Started
Tetra Aquarium 20 Gallon Kit with LED and Filter
$119.14 on Amazon
A forgiving size that opens up real community stocking.
Aqueon Aquarium Starter Kit 20-Gallon
$151.99 on Amazon
Filtration and LED to build a stable community tank.
Stock gradually after cycling
No stocking list is safe in an uncycled tank. Run a fishless cycle for about 4 to 6 weeks until ammonia and nitrite both read zero and nitrate is climbing, which proves your beneficial bacteria can process waste. Only then begin adding fish, and do it in small batches over several weeks so the bacteria colony grows to match the rising bioload. Dumping a full list into a fresh tank causes the deadly ammonia and nitrite spike behind most new-tank fish losses. Our guide on how to cycle a fish tank walks through the process.
Right-size before you stock
If you have not bought a tank yet, let the fish you want decide the size. The minimum tank size calculator shows the smallest sensible home for a given species, which often steers people up a size and saves heartbreak later. Once you have a tank, the stocking calculator turns your wishlist into a balanced plan by weighing adult size and bioload against your volume and filtration.
Pair this chart with the compatibility chart so your stock not only fits but also gets along, and the aquarium sizes chart to match dimensions to your space. Find every planning table at the reference charts hub.
Frequently Asked Questions
How many fish can I put in my tank?
It depends on tank size, the adult size of each fish, filtration, and how much you maintain the tank, not on a single tidy formula. The old one inch of fish per gallon rule fails badly for tall-bodied or messy fish. Use the example lists in this chart as tested starting points, then confirm your exact plan with our stocking calculator, which accounts for adult size and bioload.
Is the one inch per gallon rule reliable?
Not really. It treats a slim 3 inch danio the same as a chunky 3 inch goldfish, which produces far more waste and needs much more room. It also ignores territory, schooling needs, and swimming style. Treat it as a rough ceiling for small slim community fish only, and never apply it to goldfish, cichlids, or any fish that grows large. The lists here are safer.
Why is a betta the only fish in a 5 gallon list?
A 5 gallon simply does not have the water volume or swimming length for a school, and schooling fish need groups of six or more to feel secure. A single betta plus a snail or a small group of shrimp is a complete, low-bioload setup that stays stable. Adding more fish to a 5 gallon usually leads to aggression, stunting, or a crashed nitrogen cycle.
How long before I can add fish to a new tank?
Wait until the tank is fully cycled, which takes about 4 to 6 weeks with a fishless cycle. The tank is ready only when it converts ammonia to nitrite to nitrate and both ammonia and nitrite read zero. Then add fish in small batches over several weeks so the beneficial bacteria can grow to match the rising waste. Never stock a full list into an uncycled tank.
Can I keep goldfish in a 20 or 29 gallon tank?
A single fancy goldfish can start in a 20 to 29 gallon, but they grow large and are very messy, so plan on roughly 20 to 30 gallons for the first fancy goldfish and 10 to 15 more per additional one. Common and comet goldfish grow far larger and belong in ponds or very big tanks. When in doubt, give goldfish more water than feels necessary and over-filter.
What does bioload mean for stocking?
Bioload is the total waste your fish produce, which your beneficial bacteria and water changes must keep up with. Two messy fish can create more bioload than ten tiny ones, so stocking is about waste output, not just headcount. Bigger tanks and stronger filtration handle more bioload. Stock gradually, watch your parameters, and keep up water changes so the bioload never outpaces the system.
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