Biohazard
Great question: So let's revisit the 'biohazard' theme for just a moment.....
When the fish was in the single-bay garage, my wife said she couldn't be out there. She was unable, though, to identify what the smell was exactly but was leaning more toward chemical (oil, grease) than organic (mold, mildew). Since then, I've moved the car into the driveway and cleaned the rear end which had a considerable amount of road grime. Wife still thought it smelled funky until I completed the rear axle. Now, she walks by it - no problem.
Just yesterday, I asked her to sniff-check the inside. That didn't have the same happy ending, however. On the upside, the interior smell was classified as chemical and not organic. This actually makes sense since the rear seat spring bases were sprayed down with oil (the plant-based stuff) as a preservative and they are sitting inside the car. (Ditto the steel cargo deck). Interestingly, these aforementioned pieces were never treated with ammonia as I hadn't yet discovered ammonia's effectiveness in killing mold when I washed and oiled them. I do plan to take them out and spray them down with ammonia which will also remove the oil. Since I'm in the desert southwest, I'm less concerned about rust than I was in Alabama.
There's no talk of any mold odor and that's huge. Closing the car up in the garage will tell the real story.