The thing I discovered only near the end of breaking down the monkfish tail was parasites. I'm including photos and a description of everything below. If you're still interested, scroll on down...

The photos included of the monkfish tail on the main writeup of this dish have been altered slightly; this is the actual photo. Because I was so intimidated by the tail itself, I failed to notice the subtle, odd shapes highlighted here. The whole tail looks and feels pretty wierd, so I didn't notice these sub-weird things at first. I peeled the skin from the monkfish as instructed in the many youtube videos I found on doing this, none of which warned about fish parasites.

When flipping the fish over to finish pulling off the skin, I saw what I thought were a few dozen small tan-colored whiskers dangling from it. Again, because the monkfish is so odd-looking to begin with, I didn't think much of it. A good portion of these curly 'whiskers' fell out as I completed the skinning. We can see a couple of them here, but again I didn't notice nor think anything of these at this point.

I managed to make it through the removal of the silverskin almost completely, still failing to notice the scattered things highlighted here. I'm pointing these out because I was struck, in looking through these photos, that I should really have been noticing all of these things all along.

When I got the fillet to this point, I flipped it over to start cutting it away from the spine. Only then did I notice two remaining "whiskers" that had failed to fall out in my work.

And they were moving.

I pulled one of them out, and it continued to move. This was my shocking moment of realization that there were worms in this meat.

I immediately stopped and called Tokyo Fish Market. I explained that I'd found worms in the tail I'd bought from them earlier. I was transferred to a manager...he assured me that this is actually very normal. Monkfish root around in the ground and avail themselves to parasitic infection a bit more easily than other fish. The manager told me they usually try to remove them before selling them, but as long as I was cooking the fish "properly", I'd be fine.

I was a little skeptical about this when I hung up the phone, so I immediately called Monterey Fish and asked for a second opinion. The woman I spoke with uttered a groaning "Yeah" when I mentioned I'd found worms in this fish, saying it was very common and they too tried to remove as much of this as they found before selling the monkfish fillets. She also warned about cooking the fish "properly", a term that was getting more ominous to me.

I was specifically worried because both fishmongers said they prune the worms before ever cutting into the meat; I was worried that, because I hadn't been paying attention, I'd potentially cut some worms in half, leaving half of them stuck in the meat. Was this a bad thing? Especially considering a large portion of the meat would be cooked sous vide?

Hanging up the phone with Monterey Fish, I took to Twitter for more opinions. I asked:

"Chef friends: filleted monkfish tail, and only afterwards discovered some worms. Removed as many as I could see: safe to sous vide?"

The first response came within two minutes...from a friend at Alinea:

"Nope."

I stopped work in the kitchen and sat down at my laptop to read more. One can google "monkfish worms" and find several accounts of this. Almost all of these involve someone mentioning that this is very normal, just pick them out and it's fine. One of the more-comforting (?) comments was "we find parasites in vegetables and fruits all the time, and we just cut them out and continue eating without getting freaked out. The same holds true here."

I also found a bit more specific information about proper cooking temperatures for fish, which I'd never paid much attention to before. Monterey Fish and Tokyo Fish assured me that I'd be fine if I pan-fried the loins; the worms make their way out of the rapidly-heating meat and perish in the pan. But I was cooking them sous vide at a much lower temperature. Other sites noted that brining the fish overnight in salted water causes worms to crawl out of the meat, looking for lower salinity. I wasn't sure this was the right move for me either.

Finally I found a site noting that safe cooking temperature for fish is 140F; at this temperature, any parasites living in the meat that have gone undiscovered will die. Alternatively, freezing the fish in a typical household freezer for 7 days will kill any parasites. Of course, neither of these options gets rid of the parasite carcasses completely...it just assures they won't be alive when the fish is eaten.

The parasites themselves cannot survive when ingested; humans are an "end host" for them. If alive when eaten, however, they put up a hell of a fight and can cause severe gastrointestinal distress before ultimately dying. If you know someone who's gotten sick from eating at a cheap sushi place, this is almost assuredly the reason why. Sashimi-grade fish is fish that has either been frozen (as is always the case with Salmon, who, because their life cycle involves traveling between fresh- and salt-water environments, are more at--risk for parasitic infection) or found to be completely void of parasite infestation.

Unsure what my best course of action was, I drove to Berkeley Bowl to get yet another opinion and buy more monkfish fillets. The fishmonger at the counter confirmed yet again that what I was experiencing was very normal. It's difficult to find monkfish that DON'T have any worms, she noted. They too try to pick out as many worms as they can, though she admitted that it's hard to find them all, as some worms are too deeply-embedded in the meat to see easily.

I brought the monkfish from Berkeley Bowl home, and continued reading; at this point I was fascinated by all this. I found one site noting that many fish markets hold fish fillets up to bright lights to help see through them, which aids in spotting parasites. Curious about this, I did the same: I placed some white frosted plastic over a garage work light, and laid out both of the fillets I had cut myself (which had no visible worms anywhere on the surface) and the ones from Berkeley Bowl.

Here we can see mine, which look pretty clean right?

Except for the bottom-most fillet...

..in which I can clearly see this.

Of the two fillets I bought from Berkeley Bowl, one had something similar going on. And, of course, I couldn't help but wonder: even if a fillet looks totally clean, who can say if a worm HASN'T made its way through it at some point?

After a bit of thinking, I realized there didn't seem to be any way to know. Unappetizing as this was, it seemed to be a fact that I had to deal with (at least, given the resources I have for buying monkfish). I chose to try my best to push this to the side and continue with the dish. It seemed that as long as I was careful to cook each bit of the fish to at least 140F, I should be safe to eat it.

So that's what I did. The liver was poached to 145F for an hour, and only when I removed it from the water bath did I notice a small roundworm under the outer membrane. The idea of blending the liver wholesale into the mousse base (worms and all) was pretty unappetizing, so I carefully cut it into small chunks and pushed each one through a tea strainer, carefully combing through everything to prune out any dead worms I found (there were 5). The liver is mixed with fresh-from-the-boil cream and agar before blending into a mousse, so in my head this meant it had been double-cooked and was likely to be safe.

For ground monkfish loin, I again didn't love the idea of grinding up worms into my monkfish meat, so I cut one of the loins I'd checked with a light into small cubes, checked each cube again with a light to verify it was clean, then ground it up and deep-fried it. I knew the deep-drying process was pretty safe (well above 140F), so I felt confident that it too was ok to eat.

The loin en sous vide was the last piece of the puzzle, and the one for which I still have questions. The recipe directs me to cook it to 138F, which indeed seems to imply that cooking it after finding worms in it is unsafe. I chose to cook it to 143F to be safe. I don't know how other chefs get around this though; do places like Alinea just buy more monkfish than they need and discard anything that's infected? Is it possible to buy farmed monkfish? I'm curious how I could have better circumvented this problem.

I didn't offer any of the loin or the liver to Sarah; I was confident the crispy loin was clean and safe, so her plating included only it. I had decided that I was willing to test out my hypothesis of safe cooking technique on myself but not anyone else. Getting through the headgame of knowing intimately what I was doing was a challenge.

So I ate two platings of this experiment, and didn't get sick. I'm not sure if what I did was stupid or reasonable, but it was unappetizing regardless. I was able to stil critically taste and evaluate the final dish and it was indeed very tasty and well-combined, but I learned a bit too much through the course of making it to have been able to enjoy it.

I don't think I'll be in the mood for monkfish for a while.