Nano Tank Stocking Wizard
Tell us your tank size and style — get three ready-made stocking plans curated for tanks under 60 litres.
These stocking plans are guidance, not guarantees. Real bioload depends on filtration, feeding, live plants, water changes and the individual fish — always research each species and add stock gradually.
How to use the Nano Stocking Wizard
A practical walkthrough from someone who has run nano tanks for years and made most of the mistakes worth making.
What this tool actually does
The wizard takes three inputs — your tank size, the kind of community you want, and your experience level — and returns three ready-made stocking plans calibrated for tanks under 60 litres. Each plan lists compatible species, bioload scores, and care difficulty so you can compare options side by side rather than guessing. The bioload numbers come from real working tanks, not the "one inch per gallon" rule that has been killing fish since the 1990s. A 20-litre nano is not a smaller version of a 200-litre tank — it is a different ecosystem entirely, and the stocking maths has to reflect that.
Step by step
Step 1: enter your tank size. Pick the closest preset or type an exact litre value. Use the real water volume — measure it when you do a water change, not the sticker on the tank. Gravel, decoration, and wood displace water. A "20 litre" tank usually holds 16–17 litres of actual water.
Step 2: choose your vibe. The four options cover the realistic range for small tanks: peaceful community, planted nano with shrimp, biotope, or a single centrepiece fish. Be honest with yourself about the peaceful community option — most beginners want colour and activity, then end up with nipped fins and stressed fish because they picked the wrong tetras.
Step 3: set your experience level. This filters out species that need careful water parameter management. If you are within your first year of fishkeeping, take the beginner recommendation seriously. The medium-difficulty fish are not impossible — they are unforgiving.
The results show three plans ranked by fit. Each plan tells you the species, how many to stock, the combined bioload as a percentage of your tank's capacity, and whether the combination is shrimp-safe. Pick one plan and stick to it — do not cherry-pick across plans, because the bioload maths assumes the whole community.
What the results mean
Bioload score. A percentage of your filter's processing capacity. Under 60% is comfortable. 60–80% is workable with weekly water changes. Anything above 80% means you are one missed water change away from an ammonia spike. The wizard will not recommend plans above 90%.
Shrimp-safe label. Means the fish in that plan will not hunt adult cherry shrimp. It does not mean shrimp fry are safe — no fish is truly shrimp-fry-safe. If you want a colony to grow, keep shrimp alone or with otocinclus only.
Schooling indicator. Schooling fish need a minimum group size to feel secure. Six is the absolute floor for most tetras; eight is better. Below the floor, the fish will hide, lose colour, and eventually die of stress. The wizard's group sizes are non-negotiable.
Common mistakes I see
Overstocking on day one. A freshly cycled nano cannot handle full bioload. Add half the fish, wait two weeks, test ammonia and nitrite, then add the rest. The wizard's numbers assume a mature filter — at least 6 weeks old with livestock.
Mixing a betta with anything colourful. Bettas are the most common nano centrepiece and the most common reason nano tanks fail. Long-finned males will attack anything with colour or flowy fins. The wizard will not pair a betta with guppies, endlers, or other long-finned fish.
Forgetting the inverts. Shrimp and snails have negligible bioload but they are not free. A single nerite snail produces more waste than three chili rasboras. The wizard accounts for this; if you add inverts on top of a plan, you are over budget.
Frequently asked questions
Can I use this for a 5-litre pico tank?
Yes, but the only livestock options at that size are shrimp and snails. No fish belongs in a 5-litre tank, regardless of what some shop staff will tell you. The wizard will only show invertebrate plans below 8 litres.
The wizard says my tank is too small for the fish I want. Is it wrong?
Probably not. The minimum tank sizes are based on adult fish size, swimming behaviour, and territory needs — not bioload alone. A single dwarf gourami technically fits a 20-litre tank by bioload but needs 30+ litres of horizontal swimming room to behave normally. When the wizard says no, the answer is no.
Why doesn't the wizard recommend goldfish?
No goldfish — including fancy varieties — belongs in a tank under 60 litres. A single fancy goldfish needs 80+ litres and heavy filtration. "Nano goldfish" is a marketing lie. If you want goldfish, start at 80 litres and read our beginner mistakes guide first.
Can I combine two of the three recommended plans?
No — each plan already uses the full bioload budget. Combining plans puts you over capacity. If you want elements from two plans, run the full stocking calculator with your chosen mix and check the bioload there.
My tank is 65 litres. Can I still use this tool?
The wizard caps at 60 litres because beyond that, the stocking maths changes — you get more swimming room, more filtration headroom, and more species options. For tanks between 60 and 200 litres, use the standard stocking calculator instead.