Fish Tank Stocking Calculator

Summary

Enter your tank volume and add fish by name and size to see if your aquarium is safely stocked using the inch-per-gallon and surface-area methods.

How it works

1. Enter your tank volume in US gallons (or switch to liters).
2. Optionally enter tank length and width to enable the surface-area method.
3. Add each fish by name and adult body length in inches.
4. The calculator totals all fish inches and compares against your tank's capacity.
5. A color-coded load bar shows whether your tank is understocked, well-stocked, or overstocked.
6. Remove individual fish from the list to adjust your stocking plan.

Use cases

• Plan which fish to buy before setting up a new aquarium.
• Check whether adding another fish to an existing tank is safe.
• Compare stocking capacity across multiple tank sizes before purchasing.
• Teach new fishkeepers the basics of bioload and surface-area stocking rules.
• Estimate how many nano fish (such as tetras or rasboras) fit in a small tank.
• Verify that a mixed community tank stays within safe stocking limits.
• Plan a species-only tank with larger cichlids or goldfish.
• Evaluate a second-hand tank listing to understand its stocking potential.

Frequently Asked Questions