In this study, we evaluated gamete quality parameters of mature male koi carp (Cyprinus carpio) exposed to three different concentrations (1, 10, and 100 µg/L) of di-(2-ethylhexyl) phthalate (DEHP). After 60 days of exposure, there was a significant decrease in the gonadosomatic index (GSI) of males exposed to 10 and 100 µg/L of DEHP. Histological analysis of the testes revealed impaired histoarchitecture, including inflammatory cells, intratubular vacuoles, and swollen seminiferous tubules in treatment groups. Gamete quality parameters like sperm production, motility, spermatocrit, and sperm density values were significantly decreased at the 10 and 100 µg/L concentrations. Biochemical compositions, including glucose, cholesterol, and total protein levels, were significantly changed in the treatment groups. Similarly, the ionic compositions of seminal fluid (Na, K, Ca, and Mg) also varied in the treatment groups. Furthermore, the 11-ketotestosterone levels were decreased, and the 17-β estradiol levels were increased in the DEHP-treated groups. The mRNA expression levels of reproduction-related genes, including Fshr, Lhr, Ar, Erα, and Erβ, were significantly changed in the DEHP-treated males in a dose-dependent manner. In conclusion, the findings of this study confirmed that environmentally relevant exposure to DEHP may contribute to a decline in the gamete quality of male fishes.

Phthalates (diesters of phthalic acid) are widely used as plasticizers and additives in many consumer products. Laboratory animal studies have reported the endocrine-disrupting and reproductive effects of phthalates and human exposure to this class of chemicals is a concern. Several phthalates including DEHP, BBP, DBP and etc. have been recognized as substances of high concern. This study aims to systematically review the literature on effects of exposure to phthalates including ovarian effects, testicular effects, effects on reproductive hormonal level as well as gene level and effects on breeding performances in fishes. Related literature search was done through Scopus, Google Scholar, Pub-Med and the reference lists of previous review articles to identify relevant articles published in each subject area. The inclusion criteria were original research, cross-sectional studies, case-control studies, interventional studies and review articles. The search was limited to English language papers. Finally, this review paper provides all current information on the hazards of various phthalate exposures on fish reproduction. The available data demonstrate that phthalate exposure is associated with reproductive disorders in both male and female fishes. Exposure of phthalates causes alteration in reproductive gene expression level as well hormonal level, changes in gamete quality parameters and also has impacts on spawning performances in both sexes.

Di-(2-Ethyl-Hexyl) Phthalate (DEHP) is a plasticizer commonly found in aquatic environment due to wide use of plastics for various purposes. In this study, common carp (Cyprinus carpio) (length 14.2 ± 0.82 cm and weight 32.8 ± 0.66 g) were exposed to DEHP at three different concentration levels i.e., 10, 100 and 1000 ?g l-1 water for 30 d to find out its effect on certain haematological and histological parameters. Haematological studies revealed significant (p<0.05) decrease in erythrocyte counts, while leukocyte counts were significantly increased in treated group with increasing concentration of DEHP. Further, treatment of DEHP in concentration dependent manner showed deformities in erythrocytes whereas leukocytes were unaffected. The total plasma protein level was significantly (p<0.05) decreased in lower to higher concentration of the exposure. Histological studies showed gill and liver tissues were affected with impaired histoarchitecture in a dose dependent manner.