i have had a sea apple in my 75gl reef tank for 8 months now, and have had no problems. sea apple's get a bad rap, ya if they die they do create a huge problem. but then again you have to be brain dead to have it in with fish. just keep cheap fish in with them. it takes alot to irratate them. trust me, I had a rock fall right on it, it was fine.. the only thing that you have to worry about is feeding them. you should only get one if you have the time for it. they have to be fed atleast twice a day...I feed mine brine shrimp out of a turkey baster. if you buy one make shure! make shure! that it's tenticles are active. inactive tenticles are a shure sign of illness, or iritation. hope all this help's, do some recerch, there are alot of good articles about them. good luck and keep us posted