Tools you might need next
Calculate aquarium water volume in gallons and liters for rectangular, bow-front, cylinder, and corner tanks including substrate and displacement.
Calculate CO2 injection rate for planted aquariums from tank volume, target pH, KH carbonate hardness, and bubble rate for stable dissolved CO2.
Check tropical fish compatibility for community tanks by temperament, tank size, water parameters, and schooling needs before adding new species.
Usable volume subtracts substrate and decor displacement from nominal tank size.
Stocking uses adult body mass and waste habit, not juvenile size at purchase.
general guide: 1 inch slender fish per 1–2 gallons (rule varies by filtration and species)Higher turnover and mature biofilter support more bioload. Overstocking stresses oxygen and ammonia balance.
Updated: July 2026
Mix small tetras and Corydoras without exceeding filter capacity for a beginner setup.
See why heavy-waste goldfish need far more volume per fish than tropical community species.
Check remaining capacity before introducing a gourami or angel to an existing school.
Plan for adult length and territorial needs, especially cichlids and goldfish.
Uncycled tanks cannot handle full stocking. Cycle first or stock very slowly with testing.
Stock safely before you buy fish. Enter tank volume, filtration, and species profiles to estimate a sustainable fish load and avoid overcrowding.