Related to Jacks and Pompanos, these fish are found along the East Pacific coast from Baja California to Ecuador in South America. They can grow to 13 inches long, but the photo specimen, from Ecuador, was 10-1/2 inches long (7-1/2 inches without the tail), 5-1/2 inches high and 7/8 inch thick. It weighed 9-7/8 ounces. This is a typical size for those sold in Southern California. Mexican Moonfish reproduce well and are not considered threatened. They are not kosher due to lack of removable scales.
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The flesh of this fish is medium colored and medium flavored, much like the related Jacks. There is a narrow dark strip down the sides of the backbone but it is not unpleasant in taste. I do not, however, like the taste of the skin.
I have eaten this fish most successfully poached, either as skinned fillets or as a "pan dressed" fish. This fish holds together well and can be managed on the plate where I gently scrape off the skin before eating.
Buying: This fish shows up very occasionally in the Philippine fish markets here in Los Angles. It's not a fish you can just go out and buy, you deal with it when you see it.
Scales: There are no scales. There are supposedly some "scutes", which are modified scales along the lateral line near the tail. While the line can be easily seen, the scutes are difficult to detect. While scutes are technically scales, they can't be scraped off without damaging the skin, so this fish remains "unkosher".
Skin: the skin is very thin, but also strong and very elastic. It has a lot of shrink on a pan fried fillet, but doesn't give a problem with poaching. I don't like the taste and recommend removing it. Though surprisingly "stretchy", the skin can be successfully removed using the usual long knife and cutting board method. If you poach "pan dressed" fish the skin can be gently scraped off on the plate, working from the centerline to the edges.
Cleaning: The best way to handle this fish is to remove the head as shown in the photo to the left. This allows very easy removal of the innards which is difficult by any other means. The throat opening is very high and rather small, and the keel bones run full length so you'd have to make an incision on one side. The body cavity is very short and elongated vertically. To use the heads for stock you need to remove the gills, best done with a sturdy pair of long nose pliers.
Filleting: If you can't fillet this fish leaving a "see through" skeleton, you just can't fillet fish. The bone structure is complete, sturdy, and very easy to follow with a knife, and the flesh is firm. When you get to the rib cage, just cut the ribs from the backbone with kitchen shears. The ribs are very long, but few and they pull out cleanly with your long nose pliers. There are a few centerline spines that should be pulled out forward for the length of the body cavity.
Yield: A 9-7/8 ounce fish yielded 4-3/4 ounces of skin-on fillet (48%) which were 4-1/8 ounces skin removed (42%).
Cooking: The flesh of this fish remains firm enough that skinned fillets, though thin, can be poached without breaking up. Baking and similar methods will also work fine, though I recommend using skinless fillets for most purposes.
Stock: Heads, bones, and fins made a quite usable stock simmered for 1/2 hour. There was little oil but it should still be separated off using your gravy separator. I suggest not using the skins.