I posted this on another site, but haven't had any responses of note.. I'll try here. (please excuse me if it's not "proper" to post the same question on multiple online forums)
My original post was:
New 125g tank, salinity 21%, NH3
/N02 at 0ppm, N03 at 10ppm. pH is 8.2.. substrate is arragonite, rocks are tufa/lava/slate.
Fish in concern is a 5" male c.moorii - there are two males and 2 females (both males the same size, both females smaller, but same size..) no visible agrression amoung them to note. Entire population of the tank was added at once approx. 4 weeks ago. One of the c.moorii - his left pectoral fin seems injured - not like injured from being attacked -it's like the joint is red and swollen. the fish is active, eats like a pig and moves around, but each day he seems less able to move that one fin.
It's been 2 weeks since I noticed this ailment. It has slowly gotten worse. Tank conditions are the same, no other fishes showing any signs of anything. This fish is still active and loves to eat. Sometimes he swims with this fin tight up against his body as if he can't move it.. Sometimes it does flap around like he can move it. I've put some pictures here, the best my old digi-cam could take up close. Within the last 3 or 4 days, it's like a red-stringy thing is coming out of the swollen area, approx. 1/8" long. - reminds me of when (prepare to get grosed out) I got a root-canal, was awake for it, and they pulled the stringy nerve out of my tooth) Looks like a vein. Can anybody help? I've been treating the tank with Melafix, but that doesn't seem to be doing anything..
Below are the best pix I could get.. cropped and brightness/contrast boosted to try to illustrate.. none quite do this poor thing justice..
Please - any help, suggestions, medications, ANSWERS!? Is it a parasite? Wouldn't that be spreading? Again - the fish appears perfectly healthy in every respect, except this.