Insect food for aquarium fish – discover its true power

Insects, both adult and larvae, are a natural component of many fish’s diet. Therefore, ready-made foods for ornamental fish containing insects are not as surprising as in dog foods. However, another aspect is worth mentioning. With the growing interest in insects as a source of protein for livestock, companion animals and humans, they have become a popular topic of scientific research. As a result, we have extensive knowledge of their nutritional properties, which gives a whole new picture of this raw material in aquarium fish nutrition. Learn about the power of insects and the properties of a new insect food for aquarium fish – Tropical Insect Menu.

Insect fashion

The interest in insects stems from the ongoing search for alternative, planet-friendly and low-cost sources of protein with high nutritional value. Do you know the history of spirulina? If not, be sure to read the article Spirulina – a super alga for aquarium fish. The stories of chlorella, yeast and insects are similar, together with the great enthusiasm they all aroused.

About 2,000 species of insects are considered edible in the world. The most widely consumed are beetles from the order Coleoptera (31% of all eaten insects). Other frequently eaten insects include Orthopterans – grasshoppers, locusts and crickets, butterflies (Lepidoptera) and Hymenopterans such as bees, wasps and ants. It is estimated that insects are part of the daily diet of people in about 124 countries in South and Central America, Southeast Asia and Australia and Oceania.

However, eating a crunchy beetle at a Shanghai market is quite different from using insects on a large scale in the production of food for companion animals and livestock. In the latter scenario, not only a great knowledge of the biology of the species is needed, but also an idea of how to organize the entire cycle of breeding and processing of the raw material.

The development of industrial entomology over the years has been accompanied by a changing interest in various insect species. While in the 1920s.  the housefly (Musca domestica) was in the center of attention, in the early 21st century it was replaced by mealworm(Tenebrio molitor) and superworm (Zophobas morio). Today, without any doubt, the star among insects is Hermetia illucens, also known as the black fly. It is distinguished by its short development cycle and rapid biomass growth, which is crucial for industrial production.

Why is insect protein ecological?

To live, insects need much less energy and water and much less space compared to livestock. And most importantly, they efficiently convert organic plant matter into protein. This organic matter can be waste and by-products from the agri-food industry. Their high fertility and fast growth rates are additional benefits. That’s how we get organisms that can not only be used as food, but which can solve the problem of organic waste at the same time.

Insects can produce 1 kg of protein from 2 kg of food. Their protein is highly rated in terms of digestibility and the ratio of individual amino acids. However, it is worth bearing in mind that the nutritional value of insects depends very much on specific species, sex, their developmental stage and diet. Modification of the food fed to the insects significantly affects the parameters of the meal we obtain from them. This gives potentially huge possibilities in regulating the parameters of the obtained raw material.

Why do we need insect food for fish?

As you’ve probably guessed by now, insect meals have found their way into aquaculture as an alternative to expensive and phosphorus-rich fish meals. There is no doubt that they are a good ingredient for fish foods. After all, it’s a component of their natural diet. The problem lies elsewhere. Scientists are looking for answers to the question of what insects and in what quantities can be used in particular species of farmed fish to maintain certain culture parameters. Let’s not forget that this is business, so everything must be properly calculated.

Do insect foods support fish immunity?

In China, the beneficial effects of insects on human health have been known for 3,000 years. Today we know that these properties are related, among other things, to antimicrobial peptides (AMPs) present in insects. They are an important component of innate immunity. They were discovered in the early 1980s in frogs and toads. We currently know more than 1,500 such peptides from plants, fungi, bacteria and animals. In insects, they were first isolated from the pupae of the moth Hyalophora cecropia in 1980, and since then more than 150 different AMPs have been identified.

Antimicrobial peptides have antibacterial and antifungal properties. They also show activity against some parasites and viruses. Research is underway to use them as an alternative to conventional antibiotics. They may also have applications in agriculture, in controlling disease vectors (the genes responsible for AMP production are inserted into malaria-spreading mosquitoes) and in medicine. It is also believed that they can stimulate fish growth.

Chitin – a natural prebiotic from insects

Insects contain relatively few carbohydrates, usually less than 20%. However, it is worth noting that one of them is chitin, which builds the external skeletons of arthropods, including insects. Chemically, chitin has a structure similar to cellulose. Therefore, it is considered an insoluble dietary fiber with potential prebiotic properties. Chitin is not digested by monogastric animals.

With fish, this is not so obvious. Chitinase (an enzyme that breaks down chitin) has been found in many fish species. It has been produced by the fish themselves, as well as chitinolytic bacteria. The ability of fish to digest chitin varies from species to species. The results of the research show that it is quite high for marine fish, but lower for species with short digestive tracts. It is likely that the very process of chitin digestion is also affected by the composition of the fish’s diet.   

Chitin exhibits prebiotic properties, promoting the growth of lactic acid bacteria, which in turn play an important role in the breakdown of dietary fiber. Lactic acid bacteria in the gastrointestinal tract eliminate pathogenic bacteria through the production of lactic acid, hydrogen peroxide, bacteriocins and biosurfactants – surface-active compounds that make it difficult for pathogenic bacteria to colonize the gastrointestinal tract. You can read more about probiotics in aquarium fish foods in the article Probiotic foods for aquarium fish.

Many studies have shown that insect foods increase the biodiversity of the fish microbiome. Fish fed with insect foods were found to have an increase in the number of lactic acid bacteria and Bacillus sp. bacteria, and a reduction in the number of pathogenic bacteria of the Aeromonas genus. The prebiotic effect of chitin is supported by lauric acid (C12:0), of which insects are a very good source. It exhibits antimicrobial activity against Escherichia coli, Clostridium perfringens and Salmonella sp.

What are the nutritional values of insect foods for fish?

I have started with properties of insects that are most interesting from an aquarist’s point of view. However, as you probably know, insects are primarily a source of protein. The protein ranges from 42% in hermetia to 60% in silkworm pupae. In defatted raw material, the protein concentration is even higher. But every rose has its horn. The amount of protein is large, but the amino acid profile in individual insect species does not always meet 100% of the fish’s needs. The best amino acid profile can be observed in silkworm pupae meal. However, let me remind you that the parameters of the meal obtained from insects can be regulated by the diet of the insects. Numerous studies confirm that insect protein can have positive effects on fish growth, survival, nutrient digestion and homeostasis of their microbiome.

Insect foods for fish are also a very good source of fatty acids, including polyunsaturated fatty acids (PUFAs). In this aspect the leading positions belong to mealworm, house cricket and house fly.

On the other hand, they contain relatively few minerals. The exception is hermetia, which is a very good source of calcium.

Tropical Insect Menu – food for aquarium fish with insects

There are dozens, if not hundreds, of studies on the use of insects in the diet of farmed fish. In general, their goal is to determine the percentage of fish meal that can be substituted for insect meal in order to maintain the appropriate growth rate, the amount of food used and the quality of fish flesh. Most studies indicate that such replacement is possible and produces good results.

In the case of ornamental fish, the goal is quite different. We aim to provide our fish with all the necessary nutrients and functional components, affecting, for example, their coloration or improving their resistance to pathogens or the development of all external traits in breeding forms. We want our fish to be beautiful, healthy and live as long as possible. While for farmed fish it is essential to establish maximum amounts of meal from individual insects for each species, in the case of ornamental fish we are focused on getting the best out of insects.

That was the philosophy behind our Tropical Insect Menu food formula and that’s why it does not contain only one species of insect, but three. Their diverse composition complements one other – hermetia provides an adequate amount of calcium, silkworm – amino acids and unsaturated fatty acids, and mealworm – a large dose of fat. Together they make an excellent source of protein, including AMP and chitin. All three species promote the colonization of the fish’s digestive tract by probiotic bacteria, which has a huge impact on their overall health and immunity. This combination resulted in a unique food containing 45% insects (15% hermetia, 15% mealworm and 15% silkworm). It is worth noting that the proportion of individual insects in the food takes into account the latest scientific knowledge on the use of insects in fish nutrition.

Learn more about the insects used in Tropical Insect Menu food

The domestic silk moth (Bombyx mori)

Its pupae are a valuable source of protein for fish. The environmental aspect of this raw material is also worth mentioning. Its use in fish feed is part of the sustainable use of by-products generated in the textile industry.

Silkworm is particularly popular in feeding carps (Cyprinus carpio). It was observed to have an effect on higher weight gains, better feed utilization, and increased survival rates. The silkworm meal used in our foods is a defatted meal obtained from pupae and it contains as much as 74% protein and 7.5% fat.

Mealworms (Tenebrio molitor)

The mealworm is a representative of beetles (Coleoptera). It feeds primarily on plant food, however it will not disdain other insects or even carrion. Mealworm pupae are rich in protein, with an amino acid profile similar to that in soybean and salmon proteins.

The fatty acid profile resembles that found in salmon or trout. Mealworm is a good source of linoleic (Omega-6) and α-linolenic (Omega-3) acids, as well as oleic and lauric acids. It is also interesting to note that larvae also contain antimicrobial peptides. Insect Menu food uses defatted meal from mealworm pupae, which contains 66% protein and 10% fat.

Black fly (Hermetia illucens)

Hermetia illucens (Black Soldier Fly) is a species of fly from the Stratiomyidae family. Adult insects are usually 15 to 20 mm long. Interestingly, they do not have a stinger, a mouth apparatus or digestive organs, so they cannot bite and feed. They feed on protein and fat reserves that are accumulated during the larval stage. After the larval development is completed, the insect enters prepupal stage. At this stage, the larva stops feeding. It empties its guts to reduce the risk of transmitting pathogenic microorganisms.

Defatted meal from mealworm pupae used in Insect Menu contains 10% of fat, 55% of protein and essential amino acids, fatty acids, polysaccharides and trace elements. Among other food insects, hermetia is distinguished by its highest mineral content, including calcium, phosphorus and magnesium.

dr inż. (Ph.D.Eng) Aleksandra Kwaśniak-Płacheta

Literature

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