This looks like a sole? It was almost completely transparent. The photo is in focus, but it's still hard to see any detail.
Noticed there were no summer flounder listed yet. Very common species around the island. One of many caught over the summer.
En Comitán, Chiapas lo conocen cómo: bocado de cristo
A flatfish is a member of the order (Pleuronectiformes) of ray-finned demersal fishes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development. Some species face their left sides upward, some face their right sides upward, and others face either side upward.