i know that they come from brackish conditions i have a brackish tank i just wont put him in with my puffer he is evil and i love my eel i have just never switched one over to marine thanks for the info though!! everyfish guy at my petco sucks they are just young kids that dont know what their doing i usually net my own fish since i bought that eel i warned the kid that they are escape artists and he didnt listen he put the holding container on the counter next to the sink and i barely caught my new eel before he went down the drain i was pissed never will they net and bag my fish for me again!!!!!!!!