What is an Overstocked Aquarium?

An overstocked aquarium is an aquarium that either has too many fish, or is too small for the few fish it has, even if that is just one to two large fish. There are general rules of thumb for stocking both freshwater and salt water tanks, but these rules are impacted by many factors and must be adjusted as such. They are also based on very small fish and don't apply to fish that grow large. A safe rule of thumb for small-to-medium freshwater fish is 1" (2.54cm) of fish per 2.5 gallons (9.5 liters) of water, and for marine, 1" (2.54cm) of fish per 5 gallons (19 liters). In both cases one should use the adult or eventual length the fish will reach. Not the length when purchased. Otherwise your fish will outgrow your aquarium. A medium fish can be considered up to 4" (10cm) full grown. Fish that grow very large count exponentially more than fish that remain small. They require more swimming space and better filtration. They produce more waste and are often aggressive if cramped. A deep- ...  more