i had a SFE in a reef tank for six months with no problems. you should get the eel first and wait till he is settled and then get a coral when he isn't so active and looking for a home. it didn't even bother the snails or hermits, but make sure you have healthy fish, my clowns did alright till i added a new fish, got an ich outbreak and clowns seemed unhealthy, and then disappered one by one.