And sorry about the incoming long read. I'm hoping the detail will help someone pin down what this is and how to stop it. So, i have 8 peppered cories, received in two batches (one of 5, last of three) both from different shipments to the same fish store. None of the others show any symptoms at all, even the other two which he came with are eating, playing, and swimming normally. He is clamping his pectoral, pelvic, and anal fins tightly, and his caudal (tail) fin is constantly half clamped. his dorsal fin is the only normally standing fin, and his adipose fin almost looks worn down. He has a single pair of barbels, both of which look like strands from a string and about to fall off, and his mouth is barely visible. His "nose" has a dull grey patch covering it, and it stands out against the rest of his body. He is always slowly wading in the tank's slow current, which the others just lay down in or ignore, and i haven't seem him defecate or eat since i noticed him acting like this a week or so ago, shortly after i got him.
I cant verifiy that it was him, but one of the three cories did have a tiny red dot just above the base of their anal fin on the right side when i got them, but i thought it had gone away before this started. On top of this, I've had an algae outbreak since i put the last three in the tank, while having 0 ammo and nitrites, and under 10 nitrates at any point since i added them. I also had a very small patch of bluegreen algea (i think) in the center of my tank, which i was using api's E.M. Erthromycin to treat, as well as hoping that if the cory had a bacterial infection on his nose, that it would take care of it. Let it be noted the I don't have "blue green algea" anymore (i removed the few pieces of gravel with it still on it when the dosing was done), but the cory is still ill. two days ago, thinking it might be flux or an internal infection, i got kanaplex and began using it (today is the second dose).
For those wondering, My tank is a 55 gallon with eco complete black for planted tanks, has four different kinds of plants (chrismas moss, bacapo, Italian val, and a stemplant which i cannot recall the name of). It has 4 RCS (red cherry shrimp), 6 celestial pear danios, and my 8 peppers. the temperature is kept between 75 and 76.5 degrees, and is filtered by a fluval 206 canister without the carbon stage occupied.
The pictures attached are from a few days ago, but he hasn't changed much since.
