Fishmeal and fish oil have long served as important ingredients in aquafeed production, but rising prices caused by a circular market have led to the search for cheaper and more sustainable alternatives such as insects. Both black soldier flies and crickets have demonstrated huge potential as alternative aquafeed. Tests on zebrafish and African catfish using insect-based feed have provided some positive results. With more research and sustainable rearing methods, insect meal-based aquafeed can become economically-viable, improving both the quality of fish and fish culture sustainability.
Fish meal and oils have been major components in aquafeed due to their good palatability and highly digestible proteins and amino acids. However, increasing demand and unstable production have led to rising costs of aquaculture production. Furthermore, the fact that fish meals and oils are largely sourced from marine wild-caught fish populations means that this rising demand will lead to plummeting fish-stocks, with severe ecological consequences.
In light of this, researchers like Dr. Norhidayah Mohd Taufek of the Universiti Malaya have turned to insect meals as a potentially cheaper, more sustainable and perhaps even more nutritious replacement for fishmeal.
Dr. Norhidayah had studied the potential of crickets as an aquafeed component, noting their high nutritional content that has made them popular as fish bait or pet food as well as their low carbon footprint.
“My PhD work was conducted to produce formulated feed using crickets meal as a protein source for the African catfish, a commercially cultured freshwater fish in Malaysia,” Dr. Norhidayah says in regard to her research.
“Prior to this publication in 2016, there were minimal studies on insect meals for animal feed, particularly on crickets. Moreover, the work on oxidative stress reported in fish fed with insect meals was very scarce five years ago. Therefore, I could say this is the earliest study on this area concerning insect meal.”
During the study, Dr. Norhidayah and her team assigned juvenile catfish to three different diets, each containing different amounts of cricket meal.
Results indicated that a diet containing 100% or 75% cricket meal improved the growth performance of the fish in terms of body weight gain and specific growth rate.
A haematological examination of the fish demonstrated that while there is no significant differences in red blood cells in all diets, haemoglobin levels had significantly increased with increasing amounts of cricket meal in the diet.
Finally, antioxidant activity was much higher in fish fed on a 100% cricket meal diet, attributed to the presence of insect chitin. This, in addition to the antimicrobial properties of chitin and its derivatives, can improve the fish’s resistance to various diseases.
Overall, Dr. Norhidayah’s study shows that cricket meal can be used as a viable alternative to fishmeal as a protein source in fish feed.
Moving forwards to 2021, Dr. Norhidayah had focused her latest research on the black soldier fly (BSF) and thus, was captivated by a study about this subject.
This particular study explored the use of insect-based diets in nutritional programming via parental feeding/broodstock nutrition, in the hopes of producing fish stocks better adapted to feeding on sub-optimal aquafeed ingredients.
During the study, groups of zebrafish (Danio rerio) were given five experimental diets differentiated by increasing treatments of BSF prepupae meal (0%, 25%, 50%, 75% and 100%).
The results of this investigation proved to be fascinating. While no significant differences between the groups were observed in terms of growth performance, hepatic lipid accumulation and gut health, the groups that were provided with higher BSF levels (50%, 75% and 100%) showed significant downregulation of stress response markers and a positive modulation of immune responses.
Based on these results, the researchers concluded that it was possible to substitute fishmeal with 100% BSF meal without having adverse effects on later generations of fish based on the nutritional programming method.
Both this study and Dr. Norhidayah’s own demonstrate the effectiveness and economic-viability of insect-based aquafeed. And through the use of nutritional programming via parental feeding/broodstock nutrition, it is possible to increase the usage of insect meal in aquafeed formulation without causing any detrimental effects on the fish and thus improve the sustainability and production of fish cultures.
References
- Taufek, N. M., Aspani, F., Muin, H., Raji, A. A., Razak, S. A., & Alias, Z. (2016). The effect of dietary cricket meal (Gryllus bimaculatus) on growth performance, antioxidant enzyme activities, and haematological response of African catfish (Clarias gariepinus). Fish physiology and biochemistry, 42(4), 1143-1155. https://doi.org/10.1007/s10695-016-0204-8
- Zarantoniello, M., Randazzo, B., Cardinaletti, G., Truzzi, C., Chemello, G., Riolo, P., & Olivotto, I. (2021). Possible Dietary Effects of Insect-Based Diets across Zebrafish (Danio rerio) Generations: A Multidisciplinary Study on the Larval Phase. Animals, 11(3), 751. https://doi.org/10.3390/ani11030751