I read a story in the '80s (not sure when it was written) about some people who were mutants due to an environmental hazard. People ate black eggs from bubble-eyed goldfish to get high. I think the word 'freak' was in the title. Does this sound familiar to anyone?
The mention of people eating goldfish eggs to get high immediately reminded me of Freaks' Amour, a novel by Tom de Haven released in 1979, and more recently reworked as a graphic novel.
The novel deals with people coping with the aftereffects of the "Blofeld blast", an accidental radiation leak which caused massive mutations. A review here describes the story:
The main character, named Grinner, is a fish-man. He has a bit of a drug habit... the substance that gets him high is ordinary salt (that's how a classy writer puts meaning into the way his character "takes things with a grain of salt.") Grinner makes a living as an actor in a brutal kind of theater – erotic performance with other freaks and animal-people, for privileged "normal people" seeking a freak show. He wears the mask of a "normal person" on stage, but behind it his face is distorted into a permanent smile. As a mask-behind-the-mask, it puts a touch of irony on the absurdity and tragedy he experiences from the paradoxes of a fragmented world.
One of the effects of the radiation is on "pet goldfish that quadrupled in length and mass and started to anally extrude tiny, green-dappled hard-shell eggs ...". The main character's brother, Flour, cultivates these goldfish to sell their eggs as "DeathEggs, the ultimate narcotic".
The book is freely available form the Internet Archive.