This is my sailfin tang. You should notice there is a difference between mine and KimC's. Kim's is a Dajarny (sp) which is known as a Red Sea Sailfin. and mine is just the Sailfin. Both are tangs and the same in every other way except the markings, maybe mine grows slightly larger than a Red Sea. But both will need to be in a large tank, and a 90 is a little small for when Kim's grows bigger. Most tangs need to be in a tank that is six foot long. That is because they are swimmers. They love to swim. and need to swim to stay healthy. Sailfin tangs can grow to be 18inches in the wild, in our tanks more like 14inches. That is the reason for a large tank. Sailfins are like other tangs, they need a mixed diet with lots of veggies, (seaweed, kelp etc.) They can be aggressive or totally calm, depends greatly on the fish itself. But most are territorial. And will fight other fish to keep them out of what they claim as theirs. The sailfins have a small spike on their tails and sometimes they can severly hurt other fish if they start to tail whip them. Add you smaller and less territorial fish first and save the sailfin for last for a better chance of it not takeing over the tank. If you are thinking about other tangs, and them around the same time. One trick if your fish is too territorial with new fish is to move a few rocks around in his area. He wont reconize it as his own anymore and will more likely think the area belongs to the other fish, and will leave it alone. Second tip is it is not a good ideal to mix tangs of the same species, they are more likely to fight to the death. And when we say species, we ,mean same family, After the name of the tang, is an other name, usally in Latin (that no body can pronouce) that is the family name, check those names out to be sure you aren't gettin a tang from the same species.