This page will give you a general idea of the types of fish that you will find for each of the different categories of freshwater aquariums.
Tropical Community – Premium
Estimate $8 to $15 per gallon
Tropical Community – Regular
Estimate $3 to $10 per gallon
African Cichlids
Male Peacock Show Tank
Minimum Tank Size ~100 gallons
Estimate $12 to $20 per gallon
Fancy Goldfish
Minimum Tank Size ~40 gallons
Estimate $2 to $8 per gallon