Tonight I was looking closely at my halfmoon, Chroma, and it appears he has at least two tears in his fins that weren't there before the weekend. I'm no expert at diagnosing fin rot or anything, but I *suspect* that it's from his overly aggressive flaring and trying to get across his divider at his tankmate, Gamma. Gamma, meanwhile, doesn't look ragged at all and has even been busy putting up his new bubblenest since I moved him from his 2.5g tank. And I really don't think there's anything in the tank to snag his fins on either. I don't think the boys have gone at it since the one time Chroma made his way into Gamma's half of the tank on Friday. Everything is reinforced now and they've calmed down quite a bit in any case. I did an extra water change tonight, although the parameters were fine (0,0,15). I'm just going to continue doing extra changes and keep an eye on him and Gamma. I'll also have to find time in the next day or two to buy some stress coat for the poor boy too.