Even in freshwater when dealing with eels in the sense of the word, groupers eat anything they can get into their mouths, this include eels, groupers often are known to trying to eat anything larger then them, so eels fish with groupers are not advised whatsoever, for if you look for videos from divers taking shocking actions from events they see, you think twice about the idea of keeping species with something that is too well known for trying to making a meal out of a much larger marine species. This goes the same with eels being housed together, for like a spotted moray would eat another spotted moray that is just somewhat smaller, I seen this myself when I use to go diving more then 50 years ago.
Buddy
PS. Your a 8" grouper with a. 14" eel and at 14" for most any eel, the eel is very slender, slim like, groupers when feeding on eels that they can eat, they take the eel head on and draw them in slowly until the small eel is fully into its mouth.
