Fishmeal, the preferred protein source for farmed fish, faces a double blow: limited supply and rising prices. This raises concerns about the sustainability and affordability of aquaculture, the rapidly growing industry responsible for half of the fish we consume.
In this context, microalgae emerge as an alternative to replace fishmeal in aquafeeds. Various studies have highlighted the potential of using microalgae in the feeding of aquatic species.
A team of scientists from Henan University of Science and Technology and Changsha University published a scientific review on the maximum level of fishmeal substitution by microalgae and proposed the main problems and possible solutions for replacing fishmeal with microalgae.
The Potential of Microalgae
Microalgae provide a powerful protein source and a balanced amino acid profile, making them ideal candidates to replace fishmeal.
Research shows that partial substitution can even benefit fish growth, health, and feed utilization. But how much fishmeal can we replace with microalgae?
Research findings paint a promising picture. Studies demonstrate that microalgae can effectively replace significant portions of fishmeal in various fish diets, such as:
- Carp: 100% replacement of fishmeal with specific microalgae was achieved.
- Shrimp, catfish, tilapia: Replacement of up to 95% was possible with customized microalgae blends.
- Marine fish: Successful replacement of 64.1% was achieved in certain species.
- Salmon and trout: Partial substitution (25.6%-18.6%) showed positive effects.
Benefits of Microalgae Use
The benefits of using microalgae in the aquaculture industry depend on various factors, including:
- Fish species: Different fish species have different dietary needs. Carp, for example, can tolerate a complete shift to microalgae, while salmon and trout require some fishmeal for optimal growth.
- Microalgae species: Different microalgae offer different protein content and digestibility. Choosing the right species is crucial for optimal results.
- Ingredient quality: Both the quality of fishmeal and microalgae influence how fish utilize them.
- Level of fishmeal replacement: Studies suggest that replacing 100% of fishmeal protein might not be ideal for all fish. Optimal replacement levels range from 18.6% for salmon/trout to 100% for carp.
- Sustainability: Microalgae cultivation does not depend on wild fish, promoting ocean health.
- Nutritional potency: Microalgae boast high protein content and a balanced amino acid profile, crucial for fish health and growth.
- Environmentally friendly: Microalgae production can capture CO2, mitigating climate change.
Obstacles to Unveiling Microalgae’s Potential
The study identified the following obstacles limiting the potential use of microalgae in the aquaculture industry:
- Cost: Unfortunately, large-scale microalgae production remains expensive, hindering widespread adoption.
- Digestibility: Some fish species struggle to digest certain types of microalgae, requiring further research and processing techniques.
- Antinutritional factors: Certain microalgae contain compounds that may limit nutrient absorption, requiring specific solutions.
The Future
Despite the challenges, microalgae have immense potential. Researchers are actively addressing concerns about costs through innovative cultivation methods and exploring ways to improve digestibility and reduce antinutritional factors.
Microalgae have the potential to revolutionize aquafeeds by offering a sustainable and nutritious alternative to fishmeal. With continued research and innovation, these tiny powerhouses could one day help us nourish the world without sacrificing ocean health; However, many obstacles still need to be overcome to fully harness the potential of microalgae.
The study was funded by the Doctoral Scientific Research Foundation of Henan University of Science and Technology, Henan Provincial Science and Technology Research Project, and the National Natural Science Foundation of China.
Contact
Weijun Chen
College of Animal Science and Technology, Henan University of Science and Technology
Luoyang, 471000, China
Email: wjchen@haust.edu.cn
Reference
Gao, S., Chen, W., Cao, S. et al. Microalgae as fishmeal alternatives in aquaculture: current status, existing problems, and possible solutions. Environ Sci Pollut Res (2024). https://doi.org/10.1007/s11356-024-32143-1
