Fish Tank Size Calculator
Tank Size by Fish
Calculate minimum tank size based on fish count and type
Current Tank Stocking
Check if your existing tank is overstocked
Formula
Minimum gallons = number of fish x gallons per fish (based on adult size). Stocking level = total fish inches / tank gallons. Filter GPH = tank gallons x 4. Heater watts = gallons x 5.
Frequently Asked Questions
How many gallons per fish do I need?
The general rule is 1 gallon per inch of adult fish, but this varies by species. Small tropical fish (tetras, guppies) need about 2 gallons each, while goldfish need 10-20 gallons each. Always research your specific species and consider their adult size, not purchase size.
What is the minimum tank size for a betta fish?
Despite being sold in tiny cups, bettas need a minimum of 5 gallons with a heater and gentle filter. In smaller tanks, ammonia builds up quickly and temperatures fluctuate, leading to stress and disease. A 5-10 gallon tank allows proper heating, filtration, and swimming space.
Why is my fish tank cloudy?
Cloudy water is usually caused by a bacterial bloom during the nitrogen cycle (common in new tanks), overfeeding, or overstocking. Ensure your tank is properly cycled before adding fish, avoid overfeeding, maintain proper stocking levels, and perform regular water changes.
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