What is the second kind of fish Santiago ate in The Old Man and the Sea?

The second kind of fish that Santiago eats is a dolphin-fish. These are not to be confused with dolphins, those cute sea mammals that do all kinds of neat tricks at SeaWorld. Having said that, Santiago does actually say that dolphin is an excellent fish to eat cooked, which somewhat confuses the issue. But dolphins aren't fish and so Santiago can't really be referring to them. In any case, Santiago regrets not bringing salt or limes with him to flavor the raw slices of dolphin-fish he cuts from his catch.
What clinches the issue is Santiago's reference to the dolphin-fish as a dorado, which is the Spanish word for golden. A dorado is also an alternative name for the dolphin-fish. The realization that we are dealing with a dolphin-fish and not a dolphin makes it much less shocking when Santiago hooks what many readers take to be a cute sea mammal, lifts it onto his skiff, and clubs it to death before eating bits of it.