How to improve yellowtail kingfish performance at summer temperatures

Dietary lipid and protein levels influence the growth and feed utilization of Seriola lalandi at summer temperatures.

How to improve yellowtail kingfish performance at summer temperatures
Photo source: The Kingfish Company.
August 28, 2022

A team of Australian researchers found that cultivated large yellowtail kingfish (YTK, Seriola lalandi) perform better on 25% lipid diet at summer temperatures. The study, published in Aquaculture, shows an optimized diet design for both lipids and protein that can improve the YTK commercial production.

Seriola lalandi is a pelagic fish appreciated in the global fish market because of its excellent flesh quality. It is also a fast-growing species which makes it very suitable for aquaculture. YTK is also a thermosensitive fish, meaning that growth and feed efficiency can be affected outside the optimal thermal range between 20-25°C. 

Australian researchers, together with Ridley, assessed the optimum dietary protein and lipid levels for large YTK during a summer growing season. The team tested two series of diets with 25% and 30% lipids. Each series included three different diets with three different amounts of protein: 40, 44 and 48%. The six diets were tested in an 84-day experiment using 360 fish with an individual initial weight of approximately 2 kg. 

Results from final weight, biomass gain, SGR, and FCR indicated that fish fed the 25% lipids diets grew better than those fed the 30% lipids diets. Furthermore, the significant higher growth in fish fed on diet 1 (40% protein and 25% lipids) and on diet 2 (44% protein and 25% lipids) showed a better combination for large YTK raised in the summer.

Based on the combined results for 2-3.5 kg YTK from the trial, researchers suggested that the diet should contain at least 42.9% protein and 25.3% lipids. According to their results, the authors do not recommend using diet lipid levels of approximately 30% over summer periods. They emphasized that it would be uneconomical to formulate and manufacture diets containing higher protein and lipids levels.

Check out the study here.