Field studies using fish biomarkers - How many fish are enough?

► The paper focuses on biomarker variability observed in field sampling programs. ► The x-fold biomarker change is based on association to biologically-relevant effects. ► Inter-organism, inter-site and analytical variability are discussed. ► Approximate numbers of fish to collect for several fish biomarkers are provided. ► Appropriate sampling design will help identify areas of concern.