I have a fishy odor in a bedroom in my home. I have removed the carpet and padding, used a shellac(sp)/oil based paint on underfloor and walls, but the smell still comes and goes. I have not noticed it for a couple months, but then it again resurfaced tonight.
Suggestions/advice?

You think it could be coming from the air vents?

Yes, it could be coming from the air supply or even once in a while the air return. It could also be something IN your walls or even under your sub floor. Does this room have an attic where it could be coming from? Do you notice it during hot, cold days? Is it stronger or does it come back when it rains?
Mike

I have a fishy odor in a bedroom in my home. I have removed the carpet and padding, used a shellac(sp)/oil based paint on underfloor and walls, but the smell still comes and goes. I have not noticed it for a couple mths, but then it again resurfaced tonight.
Suggestions/advice??
Below this bedroom is another bedroom (basement level). There is a drop ceiling in that room but there is no smell down there at all. It seems that when the humidity is at a higher level the smell comes back. Rain or shine doesn't seem to matter. The attic is above the bedroom, but I don't think that is where the smell is because the other 2adjoining bedrooms have no smell at all.

I had a terrible fishy smell in my home-office that only arose when I plugged in a space heater. It was like some food had gone bad, or some fish had been left out to spoil. Very awful - and strong. We washed down all the surfaces in the room and even replaced the heater, but the mysterious smell persisted. We had no clue where the smell was coming from until I happened upon some posts on this site. After hearing about someone else's light socket problem, I thought I'd check out the electrical outlet our heater was plugged into -- it reeked! Turns out the heater was drawing too much electricity. I'm not sure why that produces a rotten fish smell, but the smell's gone now that switched outlets.