Silly to worry about trace amount of thiomersal in vaccines for adults when i already eat fish often? or are they totally different kinds of mercury?

Different: Thimerosal contains a different form of mercury: ethylmercury. Studies comparing the 2 note they are processed differently in the human body. Ethylmercury is broken down ; excreted more rapidly than methylmercury. Therefore, ethylmercury (the type of mercury found in the influenza vaccine) is much less likely than methylmercury (the type of mercury in fish) to accumulate in the body ; cause harm.

Yes, it's silly.: There is no need to worry about the tiny amounts of thiomersal in vaccines, especially since the preservative has been removed from children's vaccines here. It is indeed a different form of mercury that the mercury that has contaminated our seafood. In the end, the fish will get you before the thiomersal ever would.