BOSTON – The menacing monkfish is a sly, voracious predator and a coveted meal itself, with a sweet tail meat that’s earned it the nickname “the poor man’s lobster.”

The one-time trash fish is also relatively poorly understood by federal regulators. Some fishermen say that’s costing their troubled industry tens of millions of dollars annually.

In a letter last month to the Northeast region’s science chief, the Monkfish Defense Fund argued the lack of information leads federal regulators to be too cautious managing the fish, so unneeded restrictions are suppressing the catch on an abundant species.

“The Monkfish Defense Fund is committed to moving monkfish management beyond the artificial restrictions in place,” wrote the fund’s Marc Agger.

Regulators at the National Oceanic and Atmospheric Administration said they’re working with industry to fill monkfish knowledge gaps, including in such basics as its growth rates. In the meantime, caution regulating the catch is appropriate, said NOAA spokeswoman Teri Frady.

“The danger is if you don’t know enough to know how quickly these things can replace themselves, then you can’t make a good judgment about how much is too much,” she said.

The monkfish, also called goosefish, isn’t nature’s most attractive creature. If stood on its tail, it would have a sort of ice cream cone silhouette, with a thin tail that expands into a massive, spiky head.

“It’s ugly,” said Gloucester fisherman Richard Burgess.

The fish is caught from Maine to North Carolina and can grow to 4 feet long and 50 pounds. Its fang-filled mouth is flexible enough to swallow sea birds. But the monkfish also ambushes fish by stealth, using an antenna with a worm-like appendage at the end that it dangles out as a lure.

Before the 1980s, the monkfish was mainly accidentally caught by scallop and groundfish boats, most of which tossed the unwanted fish overboard, according to a 2008 report in the ICES Journal of Marine Science. But demand in Europe and Asia boosted the price, and by 2000, monkfish were worth $53 million, up from $3.5 million in 1980, according to federal statistics.

When monkfish began gaining popularity, it was managed mainly by restricting the take in the other fisheries that accidentally caught it. But by the early 1990s, fishermen and dealers were reporting signs of overfishing, including increasingly smaller monkfish.

In 1998, regulators started managing monkfish under its own plan, allowing them to better monitor the fish and decide who could chase it. It also meant more restrictions, including daily catch limits where there were none before. Fishermen today also have a maximum 40 fishing days per year.

Fishermen say that because of the restrictions, revenues fell to $19.2 million in 2010, even while the monkfish population was considered abundant.

As the monkfish prospers, fishermen who target bottom-dwelling groundfish species, such as cod, haddock and flounder, face severe cuts in catch. In an interview, Agger said maximizing the monkfish catch could make it an attractive alternative for struggling groundfishermen.

As a bonus, it also doesn’t appear more monkfish fishing would damage vulnerable groundfish stocks. Regulators say the mesh on monkfish nets is so big, smaller groundfish swim right through them.