Tennant flared his dorsal fin at me today and I noticed it looked like a small section had been taken out between the bits that hold it up? He hasn't flared before and it wasn't noticeable when it went down to half-mast. Should I do something about it or just let him be? It doesn't look infected or anything and it seems very clean, more like something done with a blade than something done by another fish or just general rot. I've only seen his fin at half mast before so I don't know how long it's been like this though. I use API stress zyme and stress coat, as well as quick start and tap water conditioner and preventative meds (Mardel Sentry Parashield and Mardel Sentry Batershield) in the quarantine tank (where he's currently living). I was planning on moving him and Eccelson to the 40 gallon breeder tomorrow and let them establish their hiding spots before I add Smith to join them as I observed him being a bit of a bully (but there's 3 fairly large mollys in a 5.5 gal quarantine so I figure that's just over crowding stress...) but his bullying was more aimed at Eccelson.

I also have Pimafix and Melafix, though I would rather not use them.

P.S. There's also a new, young, rainbow shark in the quarantine, although Rainbow Jack has been very shy so far and not at all interested in the mollys. She just hides in the castle I have in there for my Quarantiners to hide in.