We just bought a 10 pound grouper head at whole foods to use in making soup--and the gills are so red and beautiful--are they poison?
Fish gills aren't poisonous, but they aren't anything you'd want to eat. The texture is weird, they don't taste good at all.
It's cartilage, not meat. Fibrous, gelatinous, ick. Throw them into fish stock, they'll be fine. Just strain the broth to avoid fibers.
I've always avoided adding them to fish stock - I was under the impression that it can add a bitter taste.
I generally just throw the whole head into the stock and simmer slowly without problems. But Kmack is right, fish gills (and internal organs) can make for a bitter stock. And the gills on that 10-pounder are probably robust enough to be a problem.
jondotli, if you're going to continue shopping for magnificent fish heads, you should check out the traditional dish from Singapore--fish head curry. It's delicious.
I have eaten the gills from a head of salmon after I pan-fried it. They did have a strong taste and strange texture and a lot of really thin weak bones inside that I had no trouble swallowing, plus other, stronger, irregularly shaped bones around the edges that I took out carefully. Eating them would have not been the most enjoyable thing for most people, but for me they were a good addition to my meal. I will eat a lot of things that other people wouldn't like.
I had not expected that most of people only care about the taste !!
i expect well that the marine fish are rich of iodine in their gills.
I make salmon heads for my dogs; interestingly, except for my youngest lab who will eat anything that is not tacked down, my other two dogs will eat around the gills. My oldest lab did not like gills from the day she first found them in her bowl.