Many injuries or disease conditions are not caused by a specific pathogen. These can include physical damage - cuts, scrapes, contusions, hooking injuries, bites, burns - and toxic effects of chemical agents or low oxygen conditions. Fish can have other spots/lumps/patches that are not realted to a particular pathogen, injury or disease, and could be just natural variation in individual fish.
also known as
cut
scrape
bite
abrasion
Detection Methods:
gross pathology / gross clinical signs