my 75 gallon tank has been running 5 years now.havent lost a fish in like three years now.there are 2 angelfish 2 rainbows was 8 clown loaches 6 cory cats all the water test are fine a bought 3 clown loaches from big Als about a mounth ago in the last 48 hours i lost the 3 new loaches plus 3 of my big clown loaches and 2 cory cats have all died.now i see on my big 6 inch clown loach his eye is turning white?? there is no ick in the tank no white spots on any fish even the dead clowns.any help please?????