One of my fish is having bloody looking fins. The other fish in the tank doesn't seem to have a problem. Both are in a 10 gallon tank that's changed at 80% once every eight days. (The gravel is not changed.) Whenever the ammonium tests as green I put in ammonia detox and the PhD is 7.5. The temperature is kept at a stable 80-82 degrees.
The fins are somewhat raggady because about a month and a half ago, my fish jumped the barrier of the old tank and fought each other. It was REALLY bad. They've since grown back a bit.