Alabama & dame1600,
We are in a new home and have had this same problem for three years. The fishy odor only occurs in the summer months and tonight was the first time we smelled it this year. It is usually at the end of the day. I had the builder replace all the flex pipe in the upstairs HVAC system but no one has ever discovered the cause. The electric socket / fixture idea is a new one on me and apparently solves several posters' issues but doesn't explain why my (our) smell only occurs during the warmer months.
I had an inspector out at the end of last summer who ran $1,000 worth of tests just to tell me it wasn't mold or any other health or environmental issue. That provided some relief since we have two young children.
Although I don't have a solution yet, you may want to try this: take some insulation -- I used a bit from the drop down attic staircase -- and moisten it in the sink. Then seal it in a plastic bag and leave it in the attic during the day, where it will heat up. When I opened the (hot) bag, I smelled the same odor that is driving me crazy. Wet insulation puts off a fishy smell. I'm convinced I have a leak somewhere in my walls where the leaking moisture keeps wetting insulation, which puts off this smell behind the drywall. Because it only happens during the hotter time of the year, the moisture is probably in the condensation line (pipe) leading from the A/C system. I felt like I was getting closer last year and then the weather cooled to the point that the odor went away. So here I am in year four, fingers crossed that I finally get this thing solved.
Please keep me informed if either of you get anywhere. You two are the first posters that seem to be having the same problem as my family.
BTW, I'm really surprised at how many "professionals" are baffled by my problem yet so many people are posting about similar problems. I've had at least 10 inspectors, plumbers, electricians, and HVAC guys say "Wow, I've never heard of anything like this."
Q
