Fish keepers have heard the rule of thumb for stocking their aquarium. But how many fish is really too many?
Tropical fish, like any other animal, will grow at different rates, consume different amounts of food, behave with their tankmates differently and also display different levels of aggression. Depending on their metabolic processes, fish will even release a different amount of waste. The worst rule in the book is the one-fish-per-3-gallon rule.
As for stocking a freshwater aquarium, always stay conservative with how many fish you have in the tank. A light or moderately stocked aquarium will be easier to maintain and manage over one that is heavily stocked. Also, lightly stocked tropical fish aquariums fare much better in emergencies, (such as power outages) than one that is filled to the brim with livestock. This will also reduce the frequency of water changes. The general rule of a partial water change every two weeks tends to become almost every week to keep a heavily stocked aquarium healthy.
Instead of looking for a golden rule when stocking your aquarium, look for fish species that are compatible or have been compatible in other people’s experience. Look for tropical fish species that do not grow too large and are recommended for your aquarium’s size in gallons. Aquascape your aquarium to provide plenty of hiding places and retreats in the event that one fish is more aggressive than you predicted. If the tropical fish you have added seem to be getting along well and you’re not having a problem with excessive nutrients in the water you can look at adding more fish that are compatible with your current species.
Once you have established some harmony in the aquarium you can begin to research other tropical fish that may work well in your aquarium.