Experimental fish were reared in recirculating aquaculture systems at KSU’s Aquaculture Research Center, Frankfort, KY. GMT were produced through intraspecific hybridization of YY males (Fishgen Ltd) and XX females (GIFT, Louisiana Specialty Aquaculture LLC). Two additional strains of sex-reversed tilapia (SRT) produced by a commercial hatchery were obtained. All three strains (SRT-1, SRT-2, and GMT) were fed three times per day to satiation during the growth period (Figure 1). Total weight gain (WG), total feed input (TFI), feed conversion ratio (FCR), condition factor (K), and sex proportion were analyzed. Preliminary data obtained during the first six weeks revealed differences in growth rates between SRT-1, SRT-2, and GMT (Figure 2). Total feed input corresponds with growth trends illustrated in Figure 2. FCR results for SRT-1, SRT-2, and GMT were 0.917, 0.948, and 0.92. Condition factor was similar between SRT-1 (K = 2.374) and SRT-2 (K = 2.352), but lower for GMT (2.099). Sex proportion has not yet been identified. Preliminary results suggest that SRT-1 and SRT-2 may have traits of greater commercial value.
Tilapia are one of the most important groups of food fishes and a globally traded commodity. Nile Tilapia (NT) is the most cultured species among tilapias due to its commercially valuable traits. NT contributes to nearly 9% of total inland aquaculture production worldwide. The growing intensification of NT has led to the need for genetic improvement and sex control. Large-scale selective breeding programs such as Genetically Improved Farmed Tilapia (GIFT) have enhanced growth performance. Sex control methods include genetic improvement (YY males), and the use of synthetic hormones (sex reversal). Kentucky State University (KSU) addresses hormone use in NT culture and YY male technology as an alternative by evaluating intraspecific crosses of commercial strains. This study assessed the productivity traits of three genetically enhanced strains of all-male NT produced by two methods of sex control. Objectives included: (1) production of genetically male NT (GMT), (2) growth evaluation of each strain for a 90-day production trial, and (3) assessment of sex proportion amongst strains.
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