Black soldier fly (Hermetia illucens) larvae are a promising source of protein and lipid for animal feeds. The nutritional composition of the BSF larvae depend partly on the composition of the feeding medium. The BSF lipid profile in part mimics the feeding media lipid profile, and micronutrients, like minerals and vitamins, can readily accumulate in black soldier fly larvae. However, investigative studies on bioconversion and accumulation of nutrients from media to black soldier fly larvae are scarce. Here we show that inclusion of the brown algae Ascophyllum nodosum in the substrate for black soldier fly larvae can introduce valuable nutrients, commonly associated with the marine environment, into the larvae. The omega-3 fatty acid eicosapentaenoic acid (20:5n-3), iodine and vitamin E concentrations increased in the larvae when more seaweed was included in the diet. When the feeding media consisted of more than 50% seaweed, the larvae experienced poorer growth, lower nutrient retention and lower lipid levels, compared to a pure plant based feeding medium. Our results confirm the plasticity of the nutritional make-up of black soldier fly larvae, allowing it to accumulate both lipid- and water-soluble compounds. A broader understanding of the effect of the composition of the feeding media on the larvae composition can help to tailor black soldier fly larvae into a nutrient profile more suited for specific feed or food purposes.

Blood samples from healthy adult Atlantic salmon fed an optimal diet in net sea pens were collected at intervals from October to May. Haematological determinations and biochemical serum analyses were carried out on 20 fish in each of seven samples. The ranges of haematological values for sample means were: haematocrit 4449%, haemoglobin 8.9-10-4 g 100 ml-', red blood cell count 0.85-1.10 x lo'* I-', MCV 44-553 x 10-151, MCH 94-106 x g, MCHC 19.4-21.7g IOOml-' and leucocrit 0.43-0.96%. The ranges of enzyme activities in serum, for sample means, were: alkaline phosphatase 647-988 U 1-', aspartate aminotransferase 202-351 U I -' and alanine aminotransferase 4-8 U I -I . The ranges of the other parameters analyzed in serum were: total protein 41,656.6g I-', albumin 18.3-24.3 g I-', albumin/total protein ratio 39.34.0%, creatinine 26-46 pmol, triglycerides 2334.98 mmol and cholesterol 9.3-12-8 mmol. These values are considered to be the normal ranges in healthy fish. Variations due to seasonal changes, and the clinical significance of the selected parameters, are discussed. Data showing the reproducibility of the biochemical analyses in serum are presented.

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Two insect meal (IM) products were tested as ingredient in diets for Atlantic salmon weighing~250 g. The modern control diet contained 200 g kg À1 fish meal (FM100), which was stepwise replaced by insect meal A (IM A) as a 25% (A25), 50% (A50) or 100% (A100) FM replacement or insect meal B (IM B) as a 25% (B25) or 100% (B100) FM replacement. Selected nutrient parameters and contaminants were measured in the diets. After 15 weeks, fish length and weight were recorded and visceral and hepatic indices calculated. Fatty acid and amino acid digestibility was calculated. Morphology of the liver, kidney, mid-and hind intestine was evaluated. Finally, a sensory testing of the fillets was conducted. A25, A50 and A100 performed equally well as the FM100 diet. The feed intake decreased moderately with increasing IM A inclusion; however, food conversion ratio decreased, resulting in an equal net growth of the fish. Histology did not show any differences between any of the dietary groups, and sensory testing of fillets from FM100, A100 and B25 did not reveal any significant differences in odour, flavour/taste or texture between groups. IM A was suitable to replace up to 100% of dietary FM, whilst IM B did not perform equally well.

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The present work was designed to study whether changes in dietary protein quality by means of partial inclusion of fish protein hydrolysate (FPH) would alter fish growth, feed utilization, protein retention and metabolism and fish health in general. FPH was produced after hydrolysing whole minced herring using the industrial enzyme Alcalase®. The dietary protein source, low‐temperature‐dried (LT) fishmeal nitrogen was exchanged with FPH nitrogen at six levels of inclusion ranging from 0 to 300 g kg−1. The experimental diets were fed to post‐smolt (1+) Atlantic salmon (Salmo salar), with mean initial weight of 174 g for a period of 68 days. All diets were iso‐nitrogenous, iso‐energetic and contained the same amount of amino acids. Fish fed medium inclusion of FPH (180–240 g kg−1) showed a tendency to have higher feed intake than fish fed lower and higher levels of FPH inclusions. Significant higher individual specific growth rates were present in fish fed diets with 180 and 240 g kg−1 FPH when compared with those fed 300 g kg−1. Feed conversion ratio increased significantly (R2 = 0.61) and protein efficiency ratio decreased significantly (R2 = 0.59) in fish fed increased levels of FPH. Further, apparent digestibility of crude protein and the amino acids arginine, lysine, methionine and phenylalanine increased significantly with increased dietary inclusion of FPH. Plasma free amino acids, ammonium and urea indicated that FPH amino acids was absorbed earlier and nonsynchronously, and may thus be more prone to be catabolized than in those fish fed the less solubilized protein. FPH inclusion did not have an impact on fish health, as evaluated by haematology and clinical parameters.

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