 There are also many fish and invertebrates that can harm/irritate sharks such as Scorpionfish, Butterflyfish, Angelfish (large), Filefish, Triggerfish, Pufferfish, Suckerfish (over time), Porcupinefish, certain other sharks, large crabs, Hermit crabs, sea anemones, and stinging corals.Also, sharks need iodine which can be provided through regular water changes or supplements for sharks (iodine deficiencies and possibly the buildup of nitrates can result in goiter), and feeding frequency is species-specific.Copper treatments should not be administered to most shark species.