For some reason, the issue type box wouldn't let me choose "new feature", which is what this is. Anyway, for my feature a potential villager trade (maybe a slightly higher chance in farmers) would be a pufferfish and an emerald, resulting in a cooked pufferfish that only has a very slight (like 1:100) chance to have those horrible effects of the uncooked pufferfish. Alternative: the villagers give you gutted pufferfish, which you cook in a furnace for a cooked pufferfish.

In short: Pufferfish + emerald + villager = cooked pufferfish.