Im sorry fishlova, I know it is hard when we dont hear what we like, but yes, I have read articles of things redtail sharks being kept in less than ten gallons and
goldfish in bowls, that does not mean it is the right thing to do.
first off like said before the aquarium salt wont help. This fish needs a HUGE tank and need to increase the saltwater content with age; if they are not kept in a brackish tank since the beginning, they will develop lethal skin conditions and eventually die. Also, as stated before your other fish do not go with this shark.
Im sorry again, I know it can be frustrating
