both eels have never eaten a single live fish in my tank. the shark has gotten to a domino damsel. currently our tank is a 125 gallon with the marble shark, 2 snowflake eels, a clarkii clown and a DF puffer. by abbreviations i might have been misleading-RG=Royal Gramma. I thought that they find small caves that predators can't get into. both eels are sufficently trained to not eat live fish. the puffer has never harmed the clown, but the clown was quite agressive to the DD while it lasted. the puffer has seemingly "adopted" the young clarkii clown, and they are always together. from my observations the puffer taught the clown the ways of the tank. from my research, it says that marble sharks rarely ever eat tankmates. is there anyway i can protect the RG, NG, and CC's if they will be eaten, opposed to my research.