About the only thing I can find that comes close to my issue is a herpes virus found in catfish. It can lay dormant for years and then kill in 24 to 48 hrs. Both the catfish and bichir are now dead and the convict is still unaffected. I looked at the gills of the bichir and there was almost nothing to be found but was not tore up like the catfish. I don't know, but I guess I'll be researching the best way to sterilize my tank now.