Tenebrio molitor (TM) meal is a potential alternative ingredient to plant and fishmeal in aquafeeds due to its high protein content, digestibility, and low environmental impact. However, its low n-3 PUFA (EPA and DHA) content represents one of its main limitations. This study evaluated the effects of replacing fishmeal and plant-derived ingredients (plant proteins and soybean oil) with full-fat TM meal on the growth performance and lipid composition of tissues in juvenile European seabass (Dicentrarchus labrax). Four experimental diets, including 5–10% TM for replacing fishmeal and soybean oil (FM5 and FM10) and 10–20% TM for substituting plant protein ingredients and soybean oil (PI10 and PI20), were tested over 49 days against a control diet (CT). Fish fed on PI20 exhibited the highest growth performance (final weight: 49.73 g and SGR: 1.78% day−¹) compared to fish fed on FM (final weight: 47.0 g and SGR: 1.62% day−¹) and CT (final weight: 48.45 g and SGR: 1.71% day−¹). In general, the diets containing TM modulated the lipid profile in fish tissues by reducing the liver lipid content and muscle triglycerides and increasing the n-3/n-6 ratio compared to the CT diet. However, the most effective approach for modulating those parameters seems to be using the TM meal for replacing the plant ingredients instead of substituting fishmeal. Moreover, this feeding strategy, demonstrated to be useful for promoting the growth of fish owing to the use of the TM meal for replacing fishmeal, resulted in a slight reduction in the final weight of the fish.

Tenebrio molitor (TM) is considered as one of the most promising protein sources for replacing fish meal in aquafeeds, among other things because it is rich in protein, a good source of micronutrients and has a low carbon footprint and land use. However, the main drawback of TM is its fatty acid profile, in particular its low content of n-3 PUFA. This study evaluates the effects of partially replacing plant or marine-derived with full-fat TM meal at two different levels on growth performance and lipid profiles of Senegalese sole (Solea senegalensis). For this purpose, a control diet (CTRL) and four experimental isoproteic (53%) and isolipidic (16%) diets were formulated containing 5 and 10% TM meal replacing mostly fish meal (FM5 and FM10), or 10 and 15% TM meal replacing mostly plant meal (PP10 and PP15). Fish (215 g) were fed at 1% of their body weight for 98 days. The final body weight of fish fed the experimental diets containing TM meal was not different from that of fish fed the CTRL diet (289 g). However, the inclusion of TM meal resulted in a gradual improvement in growth rate and feed efficiency in both cases (replacement of fish or plant meals), and significant differences in specific growth rate (SGR) were observed between fish fed the CTRL diet (SGR = 0.30% day⁻¹) and those fed diets with the highest TM meal content (PP15; SGR = 0.35% day⁻¹). The experimental groups did not show any differences in the protein content of the muscle (19.6% w/w). However, significant differences were observed in the total lipid content of the muscle, with the FM10, PP10, and PP15 groups having the lowest muscle lipid contents (2.2% ww). These fish also showed the lowest neutral lipid content in muscle (6.6% dw), but no differences were observed in the total phospholipid content (2.6% dw). Regarding the fatty acid profile, fish fed FM10, PP10 and PP15 had lower levels of linoleic acid (18:2n-6) and higher levels of oleic acid (18:1n-9) in liver and muscle compared to fish fed CTRL. However, no differences were found between fish fed CTRL and TM-based diets for docosahexaenoic acid (22:6n-3) and total n-3 PUFA in liver and muscle. In conclusion, our study demonstrated that full-fat TM inclusion up to 15% in S. senegalensis diets had no negative effects or even some positive effects on fish survival, growth performance, nutrient utilization and flesh quality.

Sustainability enhancement is one of the main challenges of aquaculture. Since feeds represent one of the major costs from an environmental point of view, it is priority to find sustainable alterna-tive ingredients for aquaculture diet. Insect meals have some advantages as ingredients for aqua-culture, like its sustainability and nutritional value. However, the biggest drawback of full-fat in-sect meal is its fatty acid profile. The objective of this work was to assess the effects of partial plant or marine-derived ingredients replacements with full-fat Tenebrio molitor meal (TM) at two differ-ent levels on growth performance and fatty acids profiles of Solea senegalensis. For this purpose, a control diet and four experimental diets were tested, two of them contained 5 and 10% w/w TM that replaced mostly fish meal. Two other experimental diets included 10 and 15% w/w TM that replaced mostly plant meals. The inclusion of insect meal resulted in an improvement in growth rate and feed efficiency in both cases. Moreover, dietary inclusion of insect meal increased muscle total protein and decreased total lipid, without changes in phospholipids, and maintaining the relative level of n-3 PUFA. In conclusion, our study demonstrated that full-fat TM inclusion up to 15% in S. senegalensis diets had no negative effects or even positive effects on fish survival, growth performance, nutrient utilization and flesh quality.