Sex-reversed Tilapia Research Articles

Pterygoplichthys spp. (Siluriformes: Loricariidae) meal is suitable for the culture of Nile tilapia Oreochromis niloticus (Cichlidae) juveniles

ABSTRACT: We search for positive utility impact on the invasive species Pterygoplichthys spp. The optimal level of replacement of sardine meal (SM) by Pterygoplichthys spp. meal (PLM) in practical feeds for fry of Nile tilapia (Oreochromis niloticus) was evaluated. We evaluated six experimental diets: 50% PLM-50% SM, 60% PLM-40% SM, 70% PLM-30% SM, 80% PLM-20% SM, 90% PLM-10% SM and 100% PLM-0% SM. In a recirculation system, 270 sex-reversed tilapia fry were used (0.7 ± 0.1 g). Diets were administered in triplicate and the experiment lasted 56 days with sampling every 14 days. There were no statistical differences in growth. At the end of the experiment, the SGR, ADG, CF, WG, DFI, FCR and PER were determined without significant differences (P > 0.05) between treatments, but there was a tendency that could indicated higher WG and PER in the 90% PLM-10% SM treatment (93.56 ± 0.43% and 8.44 ± 1.18 g, respectively). All survival rates were higher than 90% with no significant differences. Additionally, there were no statistical differences in the chemical composition of the whole fish, while apparent digestibility coefficients of protein (81-90%) and lipids (87-93%) also showed no significant differences. We concluded that 100% PLM can replace 100% SM in feeding fry of O. niloticus without affecting their survival, growth or chemical composition or the apparent digestibility of nutrients.

Comparative Growth Performance of Genetically Male, SexReversed, and Mixed-Sex Nile Tilapia (Oreochromis niloticus) Reared in Earthen Ponds in Sagana, Kenya

Nile tilapia (Oreochromis niloticus) culture has been faced by challenges of prolific breeding and early maturity of mixed-sex tilapia that can be solved by the culture of all-male tilapia. A study was conducted to compare the growth performance, survival and condition factor of genetically male tilapia (GMT), sex-reversed tilapia (SRT) and mixed-sex tilapia (MST) cultured in earthen ponds. Fingerlings of initial weights ranging from 0.41 to 0.91 g for GMT, SRT and MST were stocked in 150 m2 earthen ponds in triplicates at 3 fish m-2 and fed on a 35% crude protein diet. After 180 days culture period, the final body weights of SRT (202.82±7.30 g) was significantly higher than GMT (174.34±3.71 g) and MST (148.06±4.60 g) (P<0.05). The survival of MST (74.11±4.73%) was higher than GMT (67.22±9.72%) and SRT (65.22±2.94%) but no significant differences were observed (P>0.05). The condition factor of all the fish was above 1 and was significantly different between the groups (P<0.05). This study demonstrates that SRT has superior growth performance than GMT and MST hence sex reversal should be used for improved Nile tilapia production.

Landmark based shape variation of normal male, female and sex-reversed tilapia (Oreochromis niloticus) in Bangladesh

The truss network systems constructed with the help of landmark were evaluated to infer the shape of normal male, female and monosex male tilapia. A total of sixty (60) individuals from different sources (Subarna Agro Based Initiative and BismillahAgro Production) were collected during September-December, 2013. All the data of the studied characteristics were obtained using the digital photograph of the samples which were analyzed through professional image measurement software. Nine morphometric and eight meristic characters were considered along with twenty six truss network measurements. Highly significant difference (P<0.05) was observed in six (SL, HL, PrDL, MBH, EL and PL) of eight morphometric measurements. In case of truss measurements 7 of 26 measurements showed highly significant differences among the groups. For both morphometric and landmark measurements the first DF accounted for 98.9% and 85.7% and the second DF accounted for 1.1% and 14.3% respectively. With truss network system 100% monosex male samples, 85.5% of normal male samples, 100% of female samples were correctly classified. In both cases, plotting discriminant functions revealed high isolation of the groups especially between the monosex groups with the other two groups. The results showed that the shape of the tested tilapia groups significantly differed from each other depending on the truss measurements. that could be explained by the genetic sex related reasons.Progressive Agriculture 26 (2): 168-172, 2015

Evaluation of Nile tilapia pond management strategies in Egypt

Five pond management strategies for Nile tilapia Oreochromis niloticus L. production were evaluated in 0.1-ha earthen ponds in Egypt during a 145-day production cycle. Pond management strategies developed by the Pond Dynamics/Aquaculture Collaborative Research Support Programme (PD/A CRSP) were compared with a traditional and a modified Egyptian pond management strategy. Young-of-year Nile (mixed-sex or sex-reversed) tilapia were stocked into ponds at 20000 fish ha(-1). Sex-reversed tilapia were stocked into chemical fertilization, organic fertilization plus formulated feed and feed only treatment ponds, whereas mixed-sex tilapia were stocked into organic fertilization plus formulated feed and chemical plus organic fertilization plus formulated feed treatment ponds. Nile tilapia yields ranged from 1274 to 2929 kg ha(-1). Nile tilapia yields in organic fertilization plus formulated feed treatments were significantly greater than the yield from chemical fertilization ponds. PD/A CRSP pond management strategies did not produce significantly greater Nile tilapia yields than the traditional Egyptian system, but a larger percentage of harvested tilapia in the organic fertilization plus feed treatments were classified in the first and second class size categories compared with the traditional Egyptian system. Organic fertilization plus formulated feed pond management strategies had the highest net returns, average rate of return on capital and the highest margin between average price and break-even prices to cover total variable costs or total costs.