Catfish to release ammonia from their gills, perhaps with what ever else is going on internally the catfish is releasing more toxins as its body appears to be eating itself.
So sad to see a cory in that situation, and I think the best course of action is to euthanize
, at least then you know it is beyond suffering.
If your other corys are all active and well, then I really don't think this wasting problem will occur in them, I really feel is it related to a point in the corys life where they where starved (purged is the term they usually use in relation to transporting live fish etc) and the gut flora never recovered. Because we don't know how the fish where prior to leaving the breeder, we have no way of knowing if the starving could of happened there when in large numbers the growing cory(s) had limited access to food, then starved/ purged for transport and then potentially not received enough food in the pet shop.
As Eaglesaquarium said other people have experienced similar issues with Pleco's and I seem to recall reading somewhere that the young pleco's need to gain their gut flora from their parents droppings. The organisms they need in their stomachs to break down the woods and things they chew on they are not born with.
I wish I could easily send you some of my excess peppered corys, but I have had bad experiences posting fish in the past and coming into winter is not a good time to post without heat packs.
Not looking good at the moment
