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Increasing global rates of diminished fertility in males has been suggested to be associated with exposure to environmental contaminants (ECs). The aquatic environments are the final repository of ECs. As the reproductive system is conserved in vertebrates, studies on the effects of ECs on fertility endpoints in fishes provide us with valuable information to establish biomarkers in risk assessment of ECs, and to understand the ECs-related fertility threat. The aim of the present review was to evaluate associations between ECs and fertility determinants to better understand ECs-related male fertility threat in male fishes. Wildlife studies show that the reproductive system has been affected in fishes sampled from the polluted aquatic environment. The laboratory studies show the potency of ECs including natural and synthetic hormones, alkylphenols, bisphenols, plasticizers, pesticides, pharmaceutical, alkylating, and organotin agents to affect fertility determinants, resulting in diminished fertility at environmentally relevant concentrations. Both wildlife and laboratory studies reveal that ECs adverse effects on male fertility are associated with a decrease in sperm production, damage to sperm morphology, alternations in sperm genome, and decrease in sperm motility kinetics. The efficiency of ECs to affect sperm quality and male fertility highly depends on the concentration of the contaminants and the duration of exposure. Our review highlights that the number of contaminants examined over fertility tests are much lower than the number of contaminants detected in our environment. The ECs effects on fertility are largely unknown when fishes are exposed to the contaminants at early developmental stages. The review suggests the urgent need to examine ECs effects on male fertility when a fish is exposed at different developmental stages in a single or combination protocol. The ECs effects on the sperm genome are largely unknown to understand ECs-related inheritance of reproductive disorders transmitted to the progeny. To elucidate modes of action of ECs on sperm motility, it is needed to study functional morphology of the motility apparatus and to investigate ECs-disrupted motility signaling.

The present study was conducted to investigate the effects of dietary water hyacinth (Eichhornia crassipes) leaves powder (WLP) on growth performance, skin mucus and serum immune response, as well as antioxidant capacity of pikeperch (Sander lucioperca). During 7 weeks culture period, 120 fish (21.2 ± 0.55 g) were fed by experimental diets containing 0% (control), 0.5%, 1% and 1.5% WLP (four treatments in triplicate). At the end of the feeding trial, results revealed a significant increase in final weight (FW), weight gain (WG), daily weight gain (DWG) and specific growth rate (SGR) in fish fed with the highest value 1.5% WLP. Furthermore, increased skin mucus total immunoglobulin (Ig) level and lysozyme (LYZ) activity was noticed in 1 and 1.5% WLP groups, protease in 1.5% WLP group, and alkaline phosphatase (ALP) in 0.5 and 1% WLP groups. Haematological evaluation showed a significant rise in red blood cell (RBC) and haematocrit (HCT) at all WLP inclusion levels, while haemoglobin (Hb) value only increased in group fed by 0.5% dietary WLP. Also, remarkable increase in LYZ, protease and alternative complement (ACH50) activity were observed in WLP‐treated groups. Moreover, higher catalase (CAT) activity was detected in WLP supplemented groups, while higher superoxide dismutase (SOD) activity was detected in 0.5 and 1.5% WLP groups. However, glutathione peroxidase (GPx) activity was higher only in 0.5% WLP group. In conclusion, the present findings showed beneficial effects of water hyacinth leaves powder as a plant‐derived growth promotor and immunostimulant in the pikeperch.

Vinclozolin (VZ) is a pesticide that acts as an anti-androgen to impair reproduction in mammals. However, VZ-induced disruption of reproduction is largely unknown in fish. In the present study, we have established a combination exposure in which adult goldfish were exposed to VZ (30 and 100 μg/L), anti-androgen flutamide (Flu, 300 μg/L), and androgen testosterone (T, 1 μg/L) to better understand effects of VZ on reproductive endocrine system. mRNA levels of kisspeptin (kiss-1 and kiss-2) and its receptor (gpr54), salmon gonadotropin-releasing hormone (gnrh3) and androgen receptor (ar) in the mid-brain, and luteinizing hormone receptor (lhr) in the testis were analyzed and compared with those of control following 10 days of exposure. kiss-1 mRNA level was increased in goldfish exposed to 100 µg/L VZ and to Flu, while kiss-2 mRNA level was increased following exposure to Flu and to combinations of 30 µg/L VZ with Flu, 100 µg/L VZ with T, and Flu with T. gpr54 mRNA level was increased in goldfish exposed to Flu and to combination of 30 µg/L VZ with Flu and 100 µg/L VZ with T. gnrh3 mRNA level was increased in goldfish exposed to 100 µg/L VZ, to Flu, and to combinations of 30 µg/L VZ with Flu, 100 µg/L VZ with T, and Flu with T. The mid-brain ar mRNA level was increased in goldfish exposed to Flu and to combinations of 30 µg/L VZ with Flu, 100 µg/L VZ with T, and Flu with T. Testicular lhr mRNA level was increased in goldfish exposed to Flu and to combination of 30 µg/L VZ with Flu. These results suggest that VZ and Flu are capable of interfering with kisspeptin and GnRH systems to alter pituitary and testicular horonal functions in adult goldfish and the brain ar mediates VZ-induced disruption of androgen production.