Walleye fingerlings (Stizostedion v. vitreum) were held in 0, 50, 100, and 150 ppm conifer-groundwood fiber at 65 F and 100% oxygen saturation for up to 190 days. Fish were contained in recirculating water-flow systems and fed daily; water and fiber suspensions were changed daily. At the end of the experiment, fish in fiber were 2 to 3% shorter in length and 6 to 11% lighter in weight than controls. Relative condition factor was unchanged. Routine metabolic rate of walleyes in 150 ppm fiber was 18% higher than controls and active metabolic rate was 15% lower. Number of mucous cells on gills of fish from 150 ppm fiber treatments was 38% lower than controls and hematocrit of fish held in fiber averaged 6% lower than controls.