Yellowtail kingfish farming is growing in Europe with high emphasis on recirculating aquaculture systems (RAS), while in Australia, Japan and Latin America the industry continues to expand predominantly through sea-cage farming. It is a carnivorous species that requires high dietary protein, and to date, fishmeal (FM) rich feeds are common to support its rapid growth. However, this brings the challenge of high phosphorus (P) content on these diets which could be poorly retained given
a more complex matrix bone-bound P, resulting in significant P excretion and discharge. The latter continues to be of environmental concern and stricter regulations governing P release to the environment are arising across the globe regardless of culture systems. With this in mind, this study aimed to aid on the management of P in Seriola farming by investigating the effects of fishmeal inclusion and dietary P levels on performance and effluent discharge.
All treatments supported strong growth, with fish increasing from an average of 65 g to approximately 350 g over the 7-week period. Importantly, no significant differences were observed in any of the performance parameters measured, including survival, specific growth rate, feed intake, or feed conversion ratio across treatments.
In the same manner, final harvest quality parameters were not significantly affected by dietary fishmeal level or total phosphorus. Proximate composition parameters, including moisture content, total phosphorus, and protein, showed no significant differences among treatments. Additionally, no significant main effects of fishmeal or total phosphorus, nor their interaction,
were observed for hepatosomatic index (HSI), viscerosomatic index (VSI), or condition factor (K). Overall, fish fed reduced fishmeal diets (30%) performed equally well as those fed increased (47% FM), indicating that lower fishmeal levels can support growth when key nutrients are balanced appropriately.
On the other hand, by reducing dietary phosphorus in low fishmeal diets decreased orthophosphorus excretion by 25% and total phosphorus discharge by 21%. P discharge values calculated as per 1000kg feed given. A similar trend was observed in high fishmeal diets, where lowering dietary phosphorus reduced orthophosphorus excretion by 36% and total phosphorus discharge by 26%.
These results confirm that mitigating environmental P emissions while sustaining performance in yellowtail kingfish farming requires an integrated approach:
optimizing total dietary P levels and employing strategic ingredient selection.
Sandeep Sharma is a Scientist in the Nutrition and Formulation team within Global R&D at BioMar. His work focuses on fish nutrition and aquafeed development, with particular expertise in amino acid nutrition, micronutrients such as vitamins and minerals, and functional feed additives. He works across a range of marine species, including yellowtail kingfish, barramundi, seabass, seabream and flatfish, supporting the development of nutrition strategies for modern aquaculture systems.
Results (13)
Efficient nutrient transfer from feed to fillet remains a key goal in sustainable aquaculture, particularly for micronutrients like vitamin D3 that carry both regulatory importance and consumer health value. Farmed salmonids are among the top contributors of vitamin D in human diets, yet the levels in fillet vary widely depending on feed formulation and production conditions.
Mechanical delousing and other handling procedures are known to trigger acute stress in Atlantic salmon (Salmo salar), leading to reduced appetite, growth losses, and a weakened physiological condition.
Largemouth bass (Micropterus salmoides) are a crucial freshwater aquaculture species in China, facing challenges like high water temperatures that cause significant economic losses. One promising solution is using functional feeds with natural antioxidants.
This study explored how different levels of synthetic vitamin D3 (cholecalciferol) supplementation influence whole body and fillet vitamin D3 deposition in rainbow trout reared under recirculating aquaculture system (RAS) conditions.
In marine fish larval rearing, the early stages are crucial for determining juvenile health, quality, robustness, and performance during on growing. This initial period is influenced by a complex interplay of factors, including egg quality, environmental conditions, and feeding and nutrition.
Managing sea lice infestations in Atlantic salmon (Salmo salar L.) aquaculture often involves mechanical treatments that can cause acute stress, reducing feed intake and compromising growth.
Fish protein hydrolysates (FPH) are known to improve nutrient availability and immune function in early-stage fish. Their high content and mix of peptides of different sizes and single amino acids, although widely variable depending on the commercial source, makes them particularly suited for fry, whose gastrointestinal tracts are still maturing.
In the past, trimmings, viscera, and heads from fisheries were often discarded as waste. However, these side-stream products, are recognized as valuable resources that can contribute to sustainable aquaculture. While the utilization of pelagic fish side-stream products is well-established, side-stream products from whitefish remain underutilized.
Atlantic salmon (Salmo salar) farming industry frequently faces the challenge of managing sea lice infestations, which necessitates mechanical treatment procedures that can stress the fish. Handling stress from crowding and delousing can negatively impact fish appetite and growth, leading to economic losses.
Iron (Fe) is a crucial trace mineral involved in various biochemical processes in fish. For Atlantic salmon (Salmo salar L.), the dietary iron requirement ranges from 60 to 160 mg/kg. However, these requirements were established using purified diets with highly bioavailable iron forms, and may not reflect the needs in practical diets where interactions with antinutrients such as phytate can affect iron bioavailability.
The global aquafeed industry has undergone a significant transformation over the past two decades, shifting from marine-based ingredients to plant-based raw materials. This transition has linked aquafeed production more closely with the environmental and social impacts of agriculture. Sustainable raw material sourcing is critical, given that aquafeed production accounts for up to 80% of the scope 3 greenhouse gas emissions in salmon farming.
The shrimp aquaculture industry faces significant challenges due to suboptimal culture conditions and susceptibility to opportunistic pathogens like Vibrio parahaemolyticus. Given the underdeveloped immune system of shrimp, these factors can lead to high mortality rates and economic losses.