how are the crayfish? invertibrates are usually the first to die when water quality issues are occuring. i would not use salt at all with the eel. pictures of your remaining fish might give a better clue to whats going on other then the flashing. how deepmis the sand and how long has it been in the tank?
ime the eel and the crays would be the first to go...if it was your regular water quality or run of the mill ick/ parasite infestation.
ime the eel and the crays would be the first to go...if it was your regular water quality or run of the mill ick/ parasite infestation.