Online Tool Store
Aquarium Stocking Calculator
Check an aquarium's stocking level against volume, filtration, and each species' adult size and temperament, before buying anything.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Fun & Misc
Aquarium Stocking Calculator
Frontend preview — no upload or external service.
Stocking check
120 litre tank at roughly 62% bioload with standard filtration — the rasbora school is under the recommended minimum of 8 to 10, and corydoras need a soft substrate rather than gravel.
How the Aquarium Stocking Calculator works
- Enter the tank's actual water volume, which is around 10% less than its rated size once substrate and decor are in.
- Add each species with the number you intend to keep.
- Read the schooling minimums and compatibility notes, not just the bioload percentage.
The method
Bioload scales with adult body mass and feeding rather than with fish count, which is why the old inch-per-gallon rule fails for larger species.
load ≈ Σ (adult size factor x count), compared against volume and filter turnover
Ten small tetras and one large cichlid can occupy the same nominal inches while producing very different waste — and needing incompatible tanks.
FAQ
Is the inch-per-gallon rule reliable?
No. It ignores adult size, body shape, waste output, and territorial behaviour. It works passably for small community fish and fails badly for everything else.
What matters more than stocking level?
Compatibility and schooling numbers. An understocked tank with a lone schooling fish or a territorial mismatch is a worse tank than a slightly heavier stocked peaceful one.
When can I add fish to a new tank?
Only after the nitrogen cycle is established, which takes weeks. Stocking a new tank fully in the first fortnight is the most common cause of losses.
How we compare
| Feature | Online Tool Store | Doing it by hand | A single-purpose app |
|---|---|---|---|
| Adult size, not purchase size | ✓ | ✗ | ✓ |
| Schooling minimums flagged | ✓ | ✗ | Sometimes |
| Compatibility notes | ✓ | Manual | ✓ |
| No account | ✓ | ✓ | ✗ |
Aquarium Stocking Calculator weighs adult size, schooling needs, and compatibility — the inch-per-gallon rule it replaces gets all three wrong.