Don't really give him feeds if stress is present ( why make him chase the food if he doesn't have to). As for gill cure, their is no cure for that, But to prevent it from getting worse, Keep water clean, keep water clean, and keep water clean. Don't add any chemicals to the tank if you don't really have to. By adding aquarium salt to the tank will help with slim coat and prevent parasites (in the gills and on the body), Keep temp high (83 to 86) , but if you are keeping water clean and water parameters good, then salt would be irrelevant.
