I have a 14" freshwater moray eel (Gymnothorax tile) and he is very healthy. he is almost alone in a 50 gallon tank... i started out with a 7" dinosaur bichir, 7 goldfish (which i successfully converted to brackish water), a silver tipped cat-shark, a silver dollar, and 2 algae eaters. i then got the moray eel... and since then (about a week) almost all of them have died. my only fish left are 2 or 3 goldfish, the moray, and the silver tipped cat-shark. my ph is good, and my salinity is at a gravity of 1.013, which is heavily brackish-ed. WHY are all of my fish dying???