What size tank do I need for fish?

Tank size depends on the species. Betta fish need 5–10 gallons solo; goldfish need 20–40 gallons per fish; oscars need 75–100 gallons; guppies need 10–20 gallons for a group. Use the species-specific calculators above for exact recommendations.

How many gallons per fish?

There is no single gallons-per-fish rule. The correct tank size depends on adult fish size, bioload, schooling requirements, and aggression. Use species-specific calculators for accurate sizing.

Fish Tank Size Calculators