Thanks, I appreciate your help.
Actually, he bounced back pretty fast overnight. His lower body is no longer grey and he is very active again. He scared me. Because I have to leave for HK to prepare my dad's funeral in a couple of days, I changed gears again and put him on Maracyn Plus (liquid form) + Prime + Kordon Fish Protector. Hopefully, he will get rid of the bacterial infection before I take off. I notice that the Kordon FP is pretty good in terms of helping with slime coat and getting Finn back to live...
This is what they say about it:
Fish•Protector forms a multi-layered protective slime co
ating on fishes' skin, protecting fishes during handling and minimizing infection. The coating works as an effective healing aid for fishes with bruises, missing scales, or frayed fins. The protective slime coating is formed by special polymer colloids, and does not involve irritating the fish’s surface by the use of salt. Fish•Protector's polymer colloids beneficially absorb medicinal dyes, e.g., methylene blue and malachite green, as well as antibiotics, e.g., oxytetracycline and itrofurazone Fish•Protector acts as a carrier for such medications and can be used as an aid in applying them to the fish’s skin. Fish•Protector combines skin slime replacers, that are more concentrated and faster working than that used in Kordon’s NovAqua Plus, with the addition of vitamin B12 and increased Echinacea, all of which aids in the normal healing process of injured fishes.