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I have 4 sterbai corys (amonst other varieties) but one has gone pale and faded its spots and isn't really eating.
The other 3 are fine and eating but just this one is pale.
The other cories are also seem fine although I did notice my ph had dropped to 6 when I removed a dw and urn with plants on it. I have since done wc and added a bit of shell grit to the internal filter and ph is back up to 6.4.
I cannot see any ich or damaged fins or anything although I did have a tetra which looked like it had a cyst on its side but I sent it quickly to tetra heaven and I had a male guppy die but who knows how old it was as I had it for quite a while.
Could this cory have something internal going on and it shows in fading spots?
Faded one:


Normal sterbai with faded one in background, plus a couple of pandas.

The nose of your pale sterbai looks normal. this really isn't my field but has the fish been 'flicking' - ie scratching itself to remove an external itch caused by a parasite etc & rubbed it's body.

Otherwise it might me a skin infection or something internal? Did this happen gradually or was it like it overnight? Did you notice anything else unusual?

I only noticed it suddenly. I wonder if it ate something off? It is still sitting around ok, just not eating or coloring up. Maybe its a stomach bug? The others are fine so far but I will keep a close eye on them all.
I have had a female bn who could pale up like that when she got upset that I moved her tank furniture.

A number of diseases can cause the pale look of your C. sterbai. Few showing this symptom survive long and the diseases belong to the incurable class.