Okay in my tank (55 gallon-planted) I have atleast 20 to 25 tetras mixed between neon, black, glowlight and pristella tetras. I also have 5 yoyo loaches (range between 2 to 3 inches to 1/2 inch due to difference in age), 6 zebra danios, a RTS, and 2 platies. My water parameters are nitrates are at 0 to20, nitrites are at 1 (did a 25% water change yesterday), GH is between soft-hard (75-150), chlorine is at 0, KH is at 80 and PH is at 7.2 between 7.8. I was treating the tank with kanaplex for a fungal infection for 3 treatments and platies are doing okay but my molly who was once fine is now acting very letheragic (trying to figure out if I can treat the tank with melafix due to loaches and any general suggestion of medication will be appreciated). To actually get to my RTS now he's just been acting strange for several days. He swims vertically on my pirate ship (he's very peaceful and has never tried to attack anyone) and won't eat. He just continues to swims in that one spot for days. His tail color is very faded with just a tint of red where it use to be very bright. I hate that he's wasting away and I can't seem to find out what's wrong with him. I even tried moving the ship for an hour and feeding them different types of food and he just searched for his ship refusing to eat then went and hid. His fin look fine and his body is completely jet black with no signs of ick or anything. My fiancee really likes this fish and I just don't know what to do. He use to come around and at least look like he was eating but not he won't leave that ship. Please help me save him! (He's been fine in my tank for over 4-5 months now and even survived moving into a new house which was 3 months ago).