It’s a rule: When you fish in places most other people do not, you catch things most other people do not. If you have followed our fishing explorations at all, you have seen that we have extended our fishing world not just by moving to new places on the ocean’s surface, but by fishing deeper…

We recently took Harmonie out to try our luck again at what is called “deep drop” fishing. There really is not a specific number for when fishing gets “deep”, but we were targeting fish at about 1200 feet (360 m). By anybody’s definition, that’s deep.

We were looking for snowy grouper, and queen snapper–which we did not find–but on our first drop to the bottom, we did hook one of these a quarter mile under the boat:

At 65 pounds, one of the bigger fish we have landed recently, the first one in a long time that took both of use to heave over the rail. I looked at as it came aboard and said, “What in the….????”

My first guess was a fish I have had at sushi restaurants, and had a vague idea what they looked like. A quick check of my references and I was pretty sure. An “escolar.” To make a long story short, after much fussing and back and forth, I have changed my mind. It’s a closely related species, an oilfish.

These are quite unusual fish in many ways. They are part of the “deep scattering layer” A dense group of fish, squid and plankton that are highly light-adverse. The very large eyes, with the intensely reflective retina are typical for a creature that hunts in near total darkness. They migrate every day from more than 1000 feet deep during the day, to near the surface at night. This is an impossible thing for most fish to do.

Fish muscle and bone is heavier than water. To counteract this, most fish have a gas filled chamber, the swim bladder, in their bodies that adjusts for this and gives the fish an overall density equal to the water they swim in, and lets them hover motionless. The problem is any fish with a normal swim bladder that tried to rise from 1000 feet deep to the surface would explode as the gas in its swim bladder increased in volume by 30 times as the pressure dropped. So a fish that needs to do this needs must have another approach.

The escolar and the oilfish solve this problem in a different way. If I can’t hold a bunch of gas to make me float, then I’ll just make the density of my muscle lower. They do this is by storing large amounts of oil in their flesh, enough to make them just about exactly the same density as water so they maintain a neutral weight in the water without having to worry about gas exploding as they migrate every night.

But these are not “oily” fish in the same way as, say, a herring. The meat is firm, snow white, and very tasty. Raw and cooked they are delicious. If you have ever had “white tuna” at a sushi restaurant, you have almost surely had escolar. If you cook these, the oil melts and runs out of the meat at an amazing rate. It’s like cooking bacon. But the oil has no “fishy” smell or taste.

There is a catch to this…

The fats these fish store in their bodies are not “normal” animal fats or fish oils. They are “waxy esters.” Humans do not have the digestive enzymes to breakdown this type of fat, so if you eat enough of it, it basically acts like a lubricant laxative. While the result is not unhealthy, it is decidedly unpleasant. The general recommendation is that a serving of 6 ounces or less is perfectly safe to eat for most people.

We have found that Bill tolerates this fish quite well as tablefare, Karen…. not so much. So we’ll just skip donating freezer space to these in the future.

I am reminded of a story from our travels several years ago, where we were in Turks and Caicos at a dock with several super yachts. The crew had been out deep drop fishing that day, and told us they had caught a large oilfish that they cooked up as a “special” dinner for the charter guests. I am guessing that this particular set of charter guests wasn’t very popular with the crew. I’m betting there was quite the impatient line for the toilet the next morning… Moral of the story: Always be nice to the help.