Aquarium Stocking Calculator
Determine the perfect number of fish for your tank
Quick Tips
Start with 25% fewer fish than calculated to allow your biological filter to establish.
Test water parameters weekly during the first month after adding new fish.
Popular Fish
Neon Tetras
Schooling fish, peaceful
Angelfish
Semi-aggressive, needs height
Corydoras
Peaceful bottom dwellers
How to Use the Aquarium Stocking Calculator: A Complete Guide
Proper aquarium stocking is crucial for maintaining a healthy aquatic environment…
Understanding Aquarium Stocking Basics
The traditional “inch per gallon” rule is a good starting point, but our calculator improves upon this by considering:
- Fish bioload: Different species produce varying amounts of waste
- Swimming space needs: Active fish require more room than sedentary species
- Filtration capacity: More efficient filters can handle larger bioloads
- Plant benefits: Live plants help with biological filtration
- Fish compatibility: Aggressive species need more space than peaceful ones
Step-by-Step Guide to Using the Calculator
1. Enter Your Tank Size
Measure your aquarium’s length, width, and height in inches, then calculate gallons using (L × W × H) ÷ 231. For rectangular tanks, this gives you the exact water volume.
2. Select Filtration Level
Choose the type that best matches your setup:
- Basic: Hang-on-back filters or small internal filters
- Moderate: Canister filters or large sponge filters
- High: Sump systems with protein skimmers (for marine tanks)
3. Choose Fish Type
Select the category that best describes your fish:
- Small Fish: Under 2 inches (tetras, guppies, rasboras)
- Medium Fish: 2-5 inches (angelfish, gouramis, rainbowfish)
- Large Fish: Over 5 inches (goldfish, oscars, plecos)
- Bottom Dwellers: Fish that primarily stay near the substrate
Interpreting Your Results
The calculator provides two key numbers:
- Recommended Fish Count: The maximum number of fish your tank can safely support
- Total Inches of Fish: The combined length of all fish at adult size
Pro Tip: Always start with 25-30% fewer fish than recommended, especially in new tanks. This allows your biological filter to establish and gives you room for error.
Frequently Asked Questions
Q: How accurate is the aquarium stocking calculator?
Our calculator provides scientifically-backed estimates based on fish bioload, oxygen requirements, and waste production. However, individual fish needs may vary, so always observe your fish’s behavior and water parameters.
Q: Can I mix different types of fish in my aquarium?
Yes, but you’ll need to calculate each species separately and ensure they’re compatible in terms of temperament, water parameters, and swimming levels. The calculator gives you a good starting point for stocking density.
Q: How often should I use the stocking calculator?
Use it whenever you’re planning to add new fish to an established tank or when upgrading your aquarium. Recalculate if you significantly change your filtration system or plant density.
Q: Does the calculator work for saltwater aquariums?
The principles are similar, but marine fish often have different space requirements. For reef tanks, we recommend using 50-75% of the freshwater recommendation due to corals’ space needs.
Q: What if my fish are juveniles? Should I calculate based on their current size?
No, always calculate based on the adult size of your fish species. Many fish grow significantly larger than their juvenile size, and overcrowding can stunt their growth and cause health issues.
