Got him 2 weeks ago from a local specialty shop. Everything has been fine until 2 days ago. These large white spots appeared. Looking with a light the skin is gone and you can see the flesh. He is swimming around. No other fish are sick. Tank is a 240 with two Sponge filters, 2 fx6 filters, and one powerhead. Other fish are a 18 inch Arowana, 2 large silver dollars, one mayain cichlid, one small jade goby. Haven't encountered spots like these in my years of keeping fish. Any ideas?

