I had an beautiful Atlantic Stingray who was eating very well and was always very healthy until I added a chemical called Algae Destroyer Advanced made by Aquarium Pharmaceuticals just to clear up a little foggy water. I had read up about the chemical before I used it and it said it was only harmful to freshwater crustaceans like shrimp and lobster. I put it in around 9:00 at night and by the next morning my baby was DEAD! My other fish are completely fine, any ideas?