First off it depends on how big he is when you get him. Also how long you depend on keeping this trigger in that tank.And for all the people that say you need a 180 gallon for a single clown trigger, i ask you all this. Do any of you have a single fish in that size tank, answer no. Everyone gives answers from books or and experience that a person had. Every fish is different in how that act. I can tell you of alot of people that have multiple triggers in the same tank and the tanks are smaller than 200 gallons. Myself being one or them.