Aquarium Stocking Calculator
Estimate the maximum number of fish for your aquarium based on tank size, filtration, and fish size. Helps maintain a healthy environment.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the Aquarium Stocking Calculator
This calculator estimates the maximum number of fish your aquarium can support based on the inch-per-gallon rule, adjusted for filtration and fish temperament.
- Enter Tank Size – Input your aquarium’s volume in gallons (e.g., 20). Use decimals if needed.
- Select Filtration Level – Choose Standard, Good, or Excellent. Better filtration allows more fish.
- Enter Adult Fish Size – Input the expected adult length of your fish in inches (e.g., 2).
- Select Fish Type – Choose Community (peaceful), Semi-aggressive, or Aggressive. More aggressive fish reduce capacity.
- Click “Calculate Stocking” – The result shows the maximum recommended number of fish. If zero, your setup cannot safely house any fish of that size.
Important: All inputs must be positive numbers. The calculator uses imperial units (gallons and inches). Always research specific fish needs beyond this general guideline.
Previous Results
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Frequently Asked Questions
A common guideline suggesting one inch of adult fish per gallon of water, adjusted for filtration and fish temperament.
Yes, the calculator includes a filtration factor: Good (1.5x) and Excellent (2x) allow more fish.
Aggressive fish require more space, so the calculator reduces capacity for semi-aggressive (0.8x) and aggressive (0.6x) types.