well, i finally have some ability to take fish photos, so here are a couple of my fantail eros, who is fighting some sort of fin rot. He is doing better, the blackness has gone away, but i don't know what else to do for him. he's in quarantine, eating and active, seems healthy, but his fins are still in shreds, so i am hesitant to move him back into the larger tank.
eros1
the second pic is better
eros2

Okaaay, that looks like residual ammonia damage to me. The blackness is actually a sign of healing, so it's a good thing. The tattered fins were probably originally caused by high ammonia / nitrites, but the white edges make me suspect bacteria has gotten a hold and finrot has set in.

What meds are you currently using to treat, and do you have any salt in the Q-tank?

my ammonia is currently under control, although i had what appeared to be a spike one morning, although it was only around .5, so i didn't think much of it. also, the other fish seemed fine. I originally treated with maroxy and maracyn 2 to cut the bacteria problems, but i had no quarantine tank, and treated all the fish together, because one(not this one) had fungus.
I moved Eros to quarantine because his fins were in terrible shape, and luciene, my moore, has been in great health since the treatment.
I have .3 level salt in my quarantine tank, and Eros is eating Medi-Gold heartily.
I don't know if I should just let him keep on in the quarantine, and wait to see how he continues to heal, or if I should treat for something else. Does anyone have any idea how long it takes fins to heal?

In good water the fins can start to heal/grow back in a matter of days. I have had fish tear fins and have them healed together the next day.

Sometimes it can be parasitic so keep an eye on it. After the ammonia/nitrite is gone and you can rule that out, parasites may be a cause.

Also, sometimes medications (strong ones like antibiotics, antiparasitics) can cause fin erosion too so it may just be left over from your previous treatment.

Also are you absolutely positive of the level of salt in there? Salt creep (repeated exposure to high salinity) can cause fin erosion too.

If I were you I would put him back in the main tank where the water is cycled and clean. Quarantine can be stressful if its uncycled and the fish is isolated and used to having other fish around. Ive had fish act like they were dying in Q only to perk up and be fine once they went back to the main tank.

Thanks for the help. Eros went back into the large tank today, and sees to be doing fine. I was worried about there being nipping from the other fish with all the fin fray to taunt her. Hope this works !

Now that the scare is over, I must admit that I read "Eros in Quarantine" and thought this post would be about something entirely different.

thats too funny, papertiger!