It would be important to know if this eel has a pectoral fin, the shape of the gill opening, the relative beginning of the dorsal and anal fins, and the presence or absence of a caudal fin. The presence of vomerine teeth and the number of head pores may be also important.

Not an expert. But to me it's a Gymnothorax species, a moray eel. Fanged teeth, bulky appearence, dorsal fin and size. It is not a fresh specimen, so most features are lost and partially the color pattern too, which is also interesting -mottled with lighter blotches on dark and not vice versa.