Farmed tilapia is currently the second most farmed finfish in aquaculture representing 5.27% of global aquaculture production. The current study assessed the effects of varying levels of krill meal (KM) incorporation in diets for broodstock of Nile tilapia, Oreochromis niloticus. The study sought to elucidate effects on spawning, egg quantity and quality, and the survival of broodstock Nile tilapia larvae produced. Three floating extruded feeds were commercially manufactured as 6.5-mm pellets. Two feeds contained krill meal (QRILL™ Aqua, Aker BioMarine Antarctic AS, Lysaker, Norway) included at 2.00 (2% KM) or 5.00% of the diet, as-is (5% KM). One commercial tilapia broodstock feed with proprietary formulation was used as a control (CTL). Twelve 40-m-3 hapas were placed in a 1,500-m-3 above ground pond to allow four replicate hapas per dietary treatment. Individual hapas were stocked with 50 females and 16 males, totaling 792 fish resulting in a 3:1 sex ratio. Total fish biomass per hapa reached 98.6 ± 11.6 kg. Four hapas were assigned for each dietary treatment. Fish were fed twice daily for 12 weeks, at 2% of the stocked fish biomass over the rearing period. Egg production exhibited a general decline over time. The control group yielded 16,066 ± 6,124 eggs per hapa, while the 2% KM diet showed a 18% increase (18,976 ± 6,417 eggs), and the 5% KM diet exhibited a 30% increase (20,947 ± 7,029 eggs). The number of spawning females declined over time, with 5% KM showing an overall 29% increase compared to the control. Egg hatching rates remained consistent, but the 5% KM diet hinted at a positive trend with 10% more larvae at day 10 despite the lack of statistical differences. Females fed KM spawned more frequently, and the 5% KM diet influenced higher fat content and elevated levels of omega-3 in Nile tilapia eggs. In addition, the EPA+DHA (8.8% in 5% KM versus 8.3% in control) and total n-3 fatty acid level (13% in 5% KM versus 12% in control) was higher in the 5% KM in comparison to control group. Both the 2% and 5% KM treatments demonstrated higher egg production, increased spawning frequency, and improved larvae survival compared to a control commercial diet. Overall, the study suggests positive effects on reproductive performance and larval survival in Nile tilapia with dietary inclusion of krill meal. The results align with earlier studies on the lipid components of KM, reinforcing its potential to enhance reproductive parameters in aquatic species.
Keywords: krill meal, tilapia, reproduction, broodstock