I have heard that oscars need vitamin C in their diet to keep them healthy...is this true? if so, what would be a good food source? if anyone feeds their oscars fruits and veggies, i'd like to know which ones are best for the fish. also, I have heard that too much protein causes digestive problems for the fish- I'd like to know how to avoid this situation because most fish foods have a very high amount of protein. any help? 