Hey Annie,

Thanks for giving us this information. It does sound like the cories brought something into the tank. Were there any ulcerous lesions on any of the fish that passed (I know you mentioned red streaks). Can you have a look at this article on fish TB and see what you think? (This is NOT the same bacteria that is what we know as human tuberculosis.) Unfortunately, the only way to positively get a diagnosis is by a necropsy (tissue samples taken and analyzed). And the other unfortunate thing is that many of the symptoms share symptoms of other diseases. But if it is strongly suspected, then you have to consider this tank contaminated... and no new fish should be introduced till the last fish in this tank passes away... and then the tank has to be nuked (with bleach AND isopropyl alcohol if the tank is glass). Is cross-contamination a factor with your other larger tank? You also have to be careful yourself, if this is fish tb... as the bacteria can be transferred to humans (again... different bacteria from what we know as human tb).

I don't want to alarm you, however, but just to make you wary and prepared. Seeing as your cories were wild-caught, and not quarantined (due to unfortunate circumstances)... this does sound like the source of your problems. However, if this is not fish tb... then I would still consider that a bacteria (or virus - which is untreatable) is present, and would avoid adding new fish to the mix - or this cycle of disease may never end.

Let us know what you think.

Michele