Caught a few when I was a kid, we ate em too, not bad from memory.
We were fishing off the cornwall coast in a rented boat, the skipper had a dustbin lashed to the deck for the catch and a big wooden table on the deck for prepping the bait, gutting or whatever. Anyway, we started to reel em in thick and fast, there were 6 of us on the boat and I think we caught about12 dogfish, 1 conga and a young blue shark. nWe let the shark go, but kept the dogfish and eel. Having never caught em before, the skipper took em off the hook and demonstrated the abrasive ability of their skin. He rasped a fish on the edge of the table, and damn, if it didn't cut through the wood like a plane.
The dogfish and eel went into the bin. When we got to shore, the conga had eaten big chunks out of some of the dogfish.