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Effect of 17β‐oestradiol on the sex ratio of tambaqui, Colossoma macropomum
Author(s) -
Reis Vanessa Ribeiro,
Almeida Fernanda Loureiro
Publication year - 2019
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/are.13878
Subject(s) - tambaqui , biology , zoology , aquaculture , sex ratio , larva , population , fish <actinopterygii> , fishery , ecology , demography , sociology
The tambaqui Colossoma macropomum is the most important native fish in Brazilian aquaculture. Females are almost 20% heavier than males and therefore are more profitable. Based on this information, we tested four different concentrations (20, 40, 80, and 120 mg/kg diet) of oestradiol (E 2 ) offered during 6 weeks to tambaqui larvae and analysed their efficiency in producing female monosex batches of the species. The study was performed in two independent tests, using different genetic backgrounds (broodstocks). All treatments increased the percentage of females in the population, but only the highest E 2 dose was “free” of males in both tests. All treated groups contained intersex individuals (when sex inversion is not complete). Plasmatic E 2 concentration was similar between treated and non‐treated fish 60 days after the treatment in fish treated with 20, 40, and 80 mg E 2 /kg diet. However, tambaqui treated with a 120 mg E 2 /kg diet showed lower E 2 plasma concentration in comparison with the control group. Last, we chlorinated the water to ensure the environmental integrity of the study. Three days after chlorination, the water was completely free of any oestradiol residue (analysed by high‐performance liquid chromatography).