Zebra mussels were tested for their mobility and strength of attachment in six diferent experimental combinations. They were kept for 7 days on copper or plastic (phenoplast) plates in 4-L beakers put on the bottom, or on plastic (resocart) plates suspended 15 mm above copper ones; water used was pure or with addition of a metal ion chelator – disodium versenate (EDTA). Exposure to copper ions resulted in the highest mortality. When the ions were EDTA-removed, the animals tended to leave copper plates and stay on the glass bottom or walls of the beakers. Attachment strength was measured with a device based on pan scales, with one of the pans replaced by forceps grasping a mussel. It was significantly lower in the presence of copper ions or with metallic substrate. Both the release of ions and the surface properties of copper substrate were found to influence zebra mussels, the former factor increasing their mortality, the latter causing sublethal responses. The observations may be useful in designing fouling-resistant devices and systems.