Determination of 17 β-estradiol residues in fish: A case study of using hormone for sex- reversal in Anabas testudineus (Bloch, 1792) in small farm in Thailand

Abstract

Abstract Several small farms in Thailand mix the 17β-estradiol with fish feed and rear the Anabas testudineus fries for 21–28 days in order to obtain the female mono-sex. However, it is important to monitoring the residues of 17β-estradiol in A. testudineus that derived from real farm. This study determined the residues of 17β-estradiol in A. testudineus fries that rearing in cement tanks in a small farm in Thailand for 3 times including, April, June and November. The 3 tanks were set as the control groups (AC) and the 3 tanks were set as hormonal treatment group (AH). The fish samples were collected at the last day of hormone treatments in each month which were at day 21st except in November, the fish samples were collected at the day 28th. After 24 hours of hormone withdrawal, the fish sample were collected to investigate the hormone residues. The result showed that the residual hormone levels in fish sample collected at the last days of AH groups showed high variation among rearing tanks and the hormone levels ranged from undetectable (ND) – 1575 ng/g while the AC group cannot be detected. The highest hormone residue in fish sample was observed in November. After hormone withdrawal for 24 hours, the residual hormone cannot be detected in all treatments indicating that there was no accumulation of 17β-estradiol in A. testudineus that expose to the hormone via feeding. The A. testudineus fries can be brought to rear further and the hormone residues should be inattentive.