Parasite Living Inside Fish Eyeball Controls Its Behavior...
In case you need a little more nightmare fuel, scientists have been studying a fish eyeball parasite. Diplostomum pseudospathaceum infects a fish's eye as a larva. While the larva grows, it causes the fish to swim slower...
https://www.neatorama.com/2017/05/04/Parasite-Living-Inside-Fish-Eyeball-Controls-Its-Behavior/
