I make my own fish emulsion by up-cycling scraps from a local fish market and fermenting it like wine/cheese. Last year I made 40 gallons. It does smell similar to fish but with a sour/sweet component and may not be acceptable in a close neighborhood but the process had virtually no smell and even vegans found the smell to be tolerable. We do have raccoons and they caused no problem.
I basically scaled up this process using a 60 gallon sealed Greek olive barrel with an airlock. Whole fish was added to a lactic acid culture with sugar, the bacteria did the rest over a few months to liquefy everything except scales and bones. So, if you want something less smelly try fish hydrolysate instead of emulsion. It is a very good amendment and made use of something otherwise thrown into the bay.
https://www.youtube.com/watch?v=tyTUQHjOfS0
The home beer maker in me thinks this sounds like a really fun and interesting project. Unfortunately, the vegan in me still thinks it sounds gross... The organic gardener in me is often at odds with the vegan in me, because so many of the organic fertilizers are based on slaughterhouse waste, manure and the like. I was hoping that buying the ready-made fish fertilizer would make it less repulsive, but the look and smell of the stuff is really pretty bad. I am hopeful that the smell will dissipate quickly. I got a gallon of the stuff, so I'm committed to trying it out. If all my fruit trees and veggies go nuts over it and start producing like crazy, I may learn to get along with it. Nasty stuff!
as a vegetarian (almost vegan), i had concerns with fish also.
but most of it is waste, and would go to waste if not used as fert.
i am pretty happy with the stuff.
lately, i have been doing more chop+drop.
using leaves, grass, coffee grounds etc...
wither making compost, or, at the base of the trees as green mulch.
in both cases, i will use the fish to wet the mulch layer (in a fairly thin solution)
THis seems to get the biology roaring.
when it rains (or gets watered) all those microbes wash down into the roots.