So far I know I am going to keep puffers The other tank mates I am unsure of I was thinking of adding a blue ribon eel. I know there is a low rate of survival, but if you can feed them live food I have seen them do very well. My plan is to feed the eel the shrimp and see if I can get him to switch over to frozen foods. If he wont I will just continue to feed the live shrimp to the eel. I like this shrimp because of its size, it becomes a adult in six months so as the eel grows i can feed it larger shrimp if need be. the tank will be 2600 to 5000 gallons that they are going into. I am waiting to here back from the Acrylic manufacturer on the size sheets they are able to make to determin the final size of the tank. I am setting up my 150 gallon tank today so once it cycles I will order the eel and let you know how it goes.