Foul Fish Smell in Homes
I am a Certified Mold Inspector and Certified Indoor Environmentalist and have encountered strange fishy odors that come and go. I investigated this problem during an inspection of a trailer in South Florida. The fishy odor was coming from an overheating breaker panel that I tracked down while using a laser thermometer. The new IR cameras also work very well at finding heat sources. In addition, I have researched this condition extensively and found it to often be the result of overheating plastic components belonging to light fixtures and switches, etc.
Warning!!! You should have a home inspector and certified electrician who uses an infrared (heat seeking camera) to find out the location of any overheating electrical components before it gets worse.
It is not unusual for air quality consultants, or bloggers on the internet to guess that this odor may be from sewer gas, mold, or rodents, etc. Such assumptions are misleading and dangerous because while your plumber is on a wild goose chase looking from sewer gas that smells like fish, the wires in your walls may be getting dangerously hot.