The term Fowlr is an acronym which stands for Fish Only With Live Rock. Fowlr tanks are exactly that, a saltwater aquarium with fish and live rock, devoid of any invertebrates and coral. The addition of any coral and inverts will probably lead to their demise, so it would be best to just stick with fish in these instances. Fowlr aquariums would typically house a variety of Triggerfish, Pufferfish, Angelfish, Butterflyfish, and other invert and coral predators, which you would never be able to put into a reef aquarium. Some of these fish can be pretty aggressive, so it would be best to research the fish you are interested in for compatibility.
