SHIMONOSEKI, Japan  Poison has been as integral to fugu, the funny-looking, potentially deadly puffer fish prized by Japanese gourmands, as the savor of its pricey meat. So consider fugu, but poison-free.

Thanks to advances in fugu research and farming, Japanese fish farmers are now mass-producing fugu as harmless as goldfish. Most important, they have taken the poison out of fugu’s liver, considered both its most delicious and potentially most lethal part, one whose consumption has left countless Japanese dead over the centuries and whose sale remains illegal in the country.

But what could be seen as potential good news for gourmands has instead been grounds for controversy: powerful interests in the fugu industry, playing on lingering safety fears, are fighting to keep the ban on fugu livers even from poison-free fish.

“We won’t approve it,” Hisashi Matsumura, the president of the Shimonoseki Fugu Association and vice president of the National Fugu Association, said of the legalization of fugu liver. He added, “We’re not engaging in this irrelevant discussion.”