Dead fish is worse. When I was in college (eons ago) they were running an inventory of the chemicals for the science classes. Someone fumbled and dropped the bottle of the chemical (about 4 oz.) and broke it. They had to evacuate the building. All 4 stories. They broke it in the basement but it permeated the building. It was 6 weeks and a professional cleaning crew before we could get back in and it still stank. We kept our jackets on and left the windows open. We even had a squirrel get in the classroom because of the open window and had to catch it in the trashcan.