Wait you mean silver tip shark? like the Columbian cat? They spawn in fresh water and migrate to salt... By 6" they should be in brackish water. Sometimes you can keep them happy in a brackish tank, some demand full salt.
well the tank is a brackish tank right now and all the levels are fine on it i've checked them at least once every couple of days and the tank is a 25 gallon tank and the filter is ment for a 30 gallon tank so it's filtering the tank fine. i just can't seem to figure out why he is doing that.