Asked by: Adam Kenedy, Agneash
Fish secrete a glyco-protein slime from the cells in their skin to make it harder for parasites to attach. Some fish even secrete toxins into the slime to deter predators.
Fish scales provide protection and reduce water turbulence. They overlap from head to tail and are only attached at the front edge. Scraping the fish from tail to head lifts the scales and wrenches them loose.