What's wrong with my Black Moor I bought 2 black Moors 2 years ago. I started off with a 10 gallon and then I

High amounts of nitrates in your water can cause the bloody fins and swim bladder issues. I'd suggest getting your water tested and see what's going on. My guess is that you aren't cleaning enough of the water often enough. Although your tank is big enough for both fish, you need to be doing weekly water changes on it. Also, get your tap water tested and make sure that is good quality.