bloody finlets

I've fallen out of the hobby a little bit and can't remember everything off the top of my head anymore- does this look like an incoming tank-wide illness or some roughhousing ? I'll be taking a bit of water in for a check tomorrow. The first photo is of the smallest bichir that is prone to some...

I’ve noticed my albino Senegal with a few bloody finlets the past 2 times I’ve done a water change. I change about 75% of the water every 4ish days. None of the other polys or fish show open wounds. Wondering if the bloody finlets is from aggression (he’s the smallest poly) or potentially from...