Fried Eel

Greasy but flavorful.
Overview
Fried Eel is a cooked dish in Stardew Valley. As with other cooking items, it can be given as a gift, but its effect depends on each villager’s preferences rather than any universal cooking rule.
In the available gift-preference data, Fried Eel is explicitly disliked by 
Like other cooked dishes, Fried Eel is part of the broader set of cooking gifts that can be used for friendship gain, but individual preferences override the general cooking category. If you are trying to improve friendship efficiently, it is better to reserve Fried Eel for villagers who like or love it rather than giving it blindly.
Official description
Greasy but flavorful.