Long‐term exposures to di‐n‐butyl phthalate inhibit body growth and impair gonad development in juvenile Murray rainbowfish ( Melanotaenia fluviatilis )

The aim of the present study was to evaluate whether long‐term exposures to environmentally relevant concentrations of di‐n‐butyl phthalate (DnBP) disrupt the reproduction‐based endpoints in juvenile Murray rainbowfish ( Melanotaenia fluviatilis ). Fish were exposed to 5, 15 or 50 µg l −1 DnBP for 30, 60 and 90 days each, and the effects on survival, body growth, whole‐body concentrations of sex steroid hormones and gonadal development were investigated. The lowest observed effective concentration to affect the condition factor after 90 days was 5 µg l −1 . Complete feminization of the gonad was noted in fish exposed to 5 µg l −1 for 90 days and to 15 and 50 µg l −1 of DnBP for 30 or 60 days. After 90 days of exposure to DnBP, the ovaries were regressed and immature as opposed to the control fish which were in early‐vitellogenic stage. Testes, present only in fish exposed to 5 µg l −1 of DnBP for 30 or 60 days, were immature in comparison to the control fish that contained testes in the mid‐spermatogenic phase. The E2/11‐KT ratio was significantly higher only after exposures to 5 µg l −1 DnBP for 90 days and 50 µg l −1 DnBP for 30 days. Our data suggest that exposures to 5 µg l −1 DnBP for 30 days did not have profound effects on body growth and gonadal differentiation of fish. However, 30 days of exposure to 15 µg l −1 could interfere with the gonad development and to 50 µg l −1 could compromise the hormonal profile of juvenile fish. Copyright © 2014 John Wiley & Sons, Ltd.