The Minimum Dietary Level and Mix Ratio of Krill Meal and Fish Meal to Elicit Feed Intake and Growth Performance in Juvenile Penaeus vannamei

Shrimp feeds depend on high levels of digestible protein and essential amino acids, which can be sourced from various commercially available feed ingredients. Marine proteins can be used to partially fulfill the requirements of these and other important nutrients. Their utilization is further influenced by their palatability and growth-promoting effect. However, marine ingredients can significantly drive costs in feed formulation depending on the type and dietary inclusion level. This study aimed to determine the minimum dietary level of fish meal (FML) and krill meal (KRM) and their mix ratio to elicit feed intake and growth performance in juvenile Penaeus vannamei . Ten diets were formulated with graded FML (90, 60, 30 g kg −1 ) in combination with 15, 30, and 45 g kg −1 KRM and a control diet with 120 g kg −1 FML. Shrimp (1.28 ± 0.08 g body weight, BW) were stocked in seventy 1-m 3 tanks (135 animals m −2 ), and after 88 days, their growth performance was determined. Feed preference was assessed through two-by-two comparisons in twenty 0.5 m 3 tanks over four weeks. No significant differences in survival (93.9 ± 4.5%), gained yield (1235 ± 92 g m −2 ), and feed conversion ratio (1.47 ± 0.09) were observed. Diets with 60 g kg −1 FML led to faster growth and higher feed intake than 30, 90, and 120 g kg −1 FML. Shrimp on 30 g kg −1 FML diets had the lowest BW, especially with 30–15 (FML-KRM) and 30–30 diets. Diets with 90 g kg −1 FML outperformed 30 g kg −1 FML. The control diet delivered a higher shrimp BW than diets 30–15 and 30–30, showing similar results to other diets except 60–15. Feed preference was influenced by KRM inclusion, with 15 g kg −1 KRM resulting in higher apparent feed intake than 30 and 45 g kg −1 . The findings indicate that FML can be effectively reduced by up to 75% when combined with lower levels of KRM. This corresponds with the industry’s ongoing trend to achieve greater sustainability and cost efficiency through the reduced utilization of critical resources.