Oh awesome, the beaches and the marshes at Port Aransas are beautiful!
Well some parasitic isopods attach to the inside of the mouth and feed on what the fish is feeding on, while others feed on mucous or blood from the fish itself. Many of these isopods cause negligible damage to the fish, and don’t seem to affect it in the long term. Some parasitic isopods that attach to the gills and draw blood from them can apparently inhibit further growth of the fish and cause it to generally slow down in its daily life. I assume these individuals are less likely to mate successfully and to escape predation
In the case of Cymothoa exigua, it appears that it atrophies the tongue of the fish by drawing off blood, and then replaces the fish’s tongue with it’s own body… it then feeds off of food the fish is eating. It is believed that it doesnt harm the fish further than this. Yes, strangely enough, the fish is able to live relatively unharmed with a parasitic isopod for a tongue!