Reproductive impairment and endocrine disruption in goldfish by feeding diets containing soybean meal

A long-term feeding experiment was conducted to investigate the inclusion of soybean meal in diets for goldfish (Carassius auratus) on fish reproduction. In the present study, 20 weeks after hatching, goldfish with an initial average weight of 2 ± 0.03 g (mean ± SD) were divided into 12 groups (three tanks per dietary treatment) and fed 400 g kg−1 crude protein diets. The four experimental diets were as follows: diet 1, fish meal (FM); diet 2, 35% soybean meal (SBM35%); diet 3, 65% soybean meal (SBM65%); diet 4, 100% soybean meal (SBM100%). After feeding with experimental diets, the impact on reproduction was investigated. In both males and females, the plasma testosterone (T) was significantly decreased, while 17β-estradiol (E2) levels were significantly increased. Levels of 17α, hydroxyprogesterone. (17-OH-P) did not differ as a result of soybean meal feeding in either males or females. The average number of eggs spawned and sperm quality were reduced on feeding with soybean inclusion. Histological examination showed impact on oocyte maturation progress and spermatogenesis process in female and male fish, respectively. In addition, feeding goldfish with soybean meal until maturation caused reduction in fertilization and hatching rates in parallel to increasing soybean meal inclusion. The results demonstrated that inclusion of soybean meal might cause sex hormone biosynthesis disruption and reproductive impairments in fish, ultimately decreased fertilization as well as hatching rates in the offspring.