Infected fish develop a variety of symptoms such as a loss of color, a dramatic decrease in activity, loss of appetite, the appearance of sores and lesions throughout the body, abdominal swelling, and finally death. It's untreatable and suspected infected fish should be euthanized immediately since its very contagious.
This effects Colisa lalia and probably accounts for a good portion of deaths in that species, the other issue is the stock quality has been declining steadily for some time due to demand. Which poor breeding techniques leads towards a lower immune system leaving the fish susceptible to viral infections such as this iridovirus. The fish 15-20 years ago were extremely hardy and now they're as fragile as glass. Unfortunately there are some fish such as neon tetras that I will never attempt again and Colsia lalia is on that list as well.