Selenium (Se) is an essential element, toxic at concentrations only slightly above those required. It can become detrimental to fish health when available in excess in the aquatic environment. This study examined the effects of Se on adult female rainbow trout, brook trout, and cutthroat trout fed Se-methionine for five months, and on their larvae. Differences between fish species and between tissues were observed in the accumulation of Se in adults, and dose-dependent effects of Se on plasma thyroid hormone concentrations in brook trout, gonad size in all three species, and indicators of oxidative stress in rainbow trout and cutthroat trout, were detected. Survival of larvae and swim-up success decreased with increasing egg Se concentrations in rainbow trout and cutthroat trout, however, the same effects were not observed in brook trout. Data from this study provide new evidence for species-specific Se accumulation and toxicity in salmonid fish. / xi, 123 leaves : ill. ; 29 cm