A recent comment spurred this post. Fish can be good in the garden. A reason to leave it out of the compost pile is because of smell and how it’d lure scavengers and flies. That said, I do add shrimp tails to my compost with little ill effect.
How to use fish properly – most recently (last summer we buried our beloved pufferfish under our newly planted larch. He’d met an early demise (though +7 years old) and so the larch marks his resting place.
Burials aside, when I was growing up I had an uncle or two who would go ‘smelting’. Smelt is a smaller, slender fish that (think anchovy-ish), I believe, have an annual ‘gathering’ of sorts and smelters net them while they are gathering at the waters edge. The uncle(s) would then give some to my father who would always bury them a couple inches under our pumpkin and squash seeds. Because they were immediately buried, we never had any type of maggot problem and seemed to have good luck with our produce. So, go ahead and bury in the heads and skeletons, staying away from the overly fleshy parts, in your garden soil. Skeletons (and shells of shrimp/lobster/crayfish) of fish contain high levels of calcium and other trace minerals that enrich the soil naturally – much better in my book than any synthetic fertilizer.