Insect meals: Sustainable feed in aquaculture

Insect meals

By Dr Lee Yih Nin

In the past, seafood products relied primarily on wild stock capture, that is, people capturing fish, crabs, prawns and so on from freshwater and marine habitats. Demand for seafood across the world is increasing, as evidenced by total fisheries and aquaculture production, which has significantly expanded from 19 million tonnes in 1950 to about 178 million tonnes in 2028.

Aquaculture is a farming method used to produce, culture and harvest fish, shellfish, algae, crustaceans, seaweed and other aquatic organisms. It is an expanding industry for food security, nature conservation, and the rebuilding and maintaining stocks of threatened and endangered species.

Fish growth and health in aquaculture highly depend on the quality of dry pellets or artificial feed. Fish grow slower and are more susceptible to diseases if fed poor-quality feed. However, producing quality artificial feed is still the biggest challenge in aquaculture because the feeding cost accounts for 50 – 70 per cent of total culture cost.

Like humans, fish need protein for amino acid production, lipids for essential fatty acids, fibre for energy, and vitamins for physiological processes. Protein is the main and costliest component in feed and fish meal (FM), which has been used as a main protein source in aquaculture for decades.

Catch fish, trash fish, or small fish often provide the protein in fish meal. The trash fish is cooked, then squeezed to remove any remaining liquids, and finally, dried and ground into fine powder.

FM is an expensive protein source and would not be able to meet the increasing growth of the aquaculture industry. Looking for alternative protein sources is thus essential for sustainable aquaculture.

Few alternative protein sources have been explored and used as FM replacements (Figure 1). Still, each alternative comes with its advantages and limitations. For example, plant-based proteins have been extensively studied as potential FM replacements but are still not considered the most suitable substitutes due to their anti-nutritional factor.

Due to their availability and sustainability, fishery by-product wastes such as fishbone meal have shown promising results as FM replacements. Insect proteins such as black soldier flies have also become popular in the search for alternative proteins. This popularity is due to several reasons: (1) variety in nutritional composition, (2) high crude protein content, (3) availability and sustainability.

Figure 1: Protein sources used in aquafeed

Among the insect species tested and used in aquafeed production, the most promising are the following species: silk worms, black soldier flies, houseflies, mealworms and crickets. Black soldier flies are the most studied in aquaculture due to the following: (1) shorter life cycle, (2) easy harvesting, (3) high crude protein content. Thus, they are valuable and potential protein sources to make sustainable aquafeed.

Recently, insect protein in fish feed has promoted gut health and microbiota changes and enhanced immunity. While insect protein has gained interest in replacing FM, a consumer behaviour study on using insect protein in aquaculture demonstrated that consumer acceptance of using insect protein remains moderate to acceptable at best.

Another critical point of using insect meals is the quality of insect sources and processing methods. It has been found that the nutritional composition of insect meals changed according to the culture condition, such as the type of subtracts they were fed. Different processing methods affect nutrient isolation, changing the percentage and effect of replacing FM in aquafeed.

Based on recent studies, the aquaculture industry will soon offer insect meals to partially or fully replace FM, depending on the culture species. More products derived from insect meal are now comparable to plant-based proteins, and products such as crude protein, chitins, oils, and antimicrobial peptides can be found in insect meals. All these derivatives have contributed to fish growth and immunity.

Insect meals are undoubtedly one of the sustainable feed components that can be used as FM alternatives in aquafeed. However, we should consider the processing methods, quality, and sources of insects before using them in aquafeed to ensure they are safe for fish and human consumption.

Dr. Lee Yih Nin is currently Assistant Director of the Curtin Aquaculture Research Laboratories (CARL) at Curtin University Malaysia, where is also a researcher and lecturer. She obtained her PhD in Veterinary Medicine from Nippon Veterinary and Life Science University (NVLU), Japan, her Master’s degree in Aquaculture from Universiti Malaysia Sabah (UMS), and Bachelor of Science in Biological Sciences from Universiti Malaysia Terengganu (UMT). Her research interests include fish nutrition, fish diseases and immunology. She is experienced in lower fungi identification, gene expression, and immunology study in fish. Dr. Lee can be contacted at leeyihnin@curtin.edu.my