Semen from brown trout ( Salmo trutta) and rainbow trout ( Salmo gairdneri) was subjected to minimal and maximal damage treatments. Spermatozoa were removed by discontinuous density gradient centrifugation for minimal damage samples and by centrifugation after plunging in liquid nitrogen for maximal damage samples. Seminal plasma samples were then analyzed for mineral, glutamic oxalacetic transaminase (GOT), lactate dehydrogenase (LDH) and total amino acid content. There were significant ( P<0.05) increases in potassium and ammonia and highly significant ( P<0.01) increases in phosphorus, magnesium, GOT, LDH and 16 amino acid levels in brown trout seminal plasma after maximal damage treatments. Sodium and calcium content decreased significantly ( P<0.05) while no significant ( P<0.05) differences occurred in boron, zinc or cysteic acid content after maximal damage treatments. However, in rainbow trout seminal plasma after maximal cell damage, zinc levels decreased significantly ( P<0.05), and calcium decreased highly significantly ( P<0.01). Phosphorus, GOT, LDH and 10 amino acid levels increased highly significantly ( P<0.01) and 4 amino acid levels increased significantly ( P<0.05). There were no differences ( P<0.05) in potassium, sodium, magnesium, boron or 4 amino acid levels in the latter species. Changes in GOT and LDH content are most applicable to monitoring cellular damage for semen processing techniques.