We started out out with two 50 gal. aquarium. Our fish grew bigger. Now its been a year and a half with our two seventy five gal. aquariums and the fish are outgrowing the tanks. We either have to split up the fish to a third tank or go to the next size bigger tank which is a hundred gallons. The problem with that is that one hundred gal. tanks are thicker glass and heavier and very pricey.