Thanks for your response. I couldn't agree with you more about the difficulty and risks involved in making long distance diagnoses (more on that later). The algae eater's never been harrassing "Dopey". My question was only to see if there was a known disorder with Corydoras which corresponds to what I'm seeing. As I said in my posting, I am really new at this. BTW: I am a physician, a diagnostic imaging specialist ("radiologist") and some of my work does include long distance diagnosis over the internet, but those are digitized medical imaging studies. With best wishes, Levantcat.
Welcome to Scotcat. It's difficult enough identifying ailments in one's own tanks. Offering diagnosis and treatment advice on the internet is rarely productive. I can only repeat the advice I give to anybody with persistant problems which is to increase your water changes both in quantity and frequency.
With your own specific setup I would say some of your fish have very different requirements in terms of water conditions. Also the Asian algae eater may be harassing your catfish. It's perhaps a little on the warm side too.
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