EMBRYO VS. DRY ARTEMIA CYSTS

Nutrition is the most important factor for rearing larvae, and despite significant progress in the fish feed industry, there is still no artificial feed that completely replaces brine shrimp eggs. Artemia nauplii are considered indispensable live food for rearing the larvae of most marine fish and crustacean larvae (Sorgeloos et al., 2001; Kolkovski et al., 2004). The biochemical composition of artemia fully satisfies the nutritional needs of most aquaculture species (Watanabe et al. 1978, 1980), it is rich in easily digestible proteins and essential fatty acids.

For most marine aquaculture species, the sustained production of high quality juveniles is a major challenge. The high and unpredictable mortality rate (sometimes over 80%) in the first weeks after hatching of marine fish larvae is a complex problem to be addressed. Other observed symptoms are stunted fish growth, malformations and a lack of reproducibility. Accumulated scientific data and experience in hatcheries for various fish, shrimp and shellfish species support the hypothesis that harmful interactions between fish and microbes are the cause (Støttrup 1993; Vadstein et al. 2004). Compared to terrestrial animals, aquatic animals live in a “hostile” environment with a high bacterial load (Verschuere et al. 2000), because fish, food and excreta are located in the same matrix - in the rearing water.

During the incubation of dry Artemia cysts, the nauplia breaks through the complex cyst membrane, consisting of two main areas: the outer chorionic layer, secreted by the glandular membrane, and the inner one, that includes the embryonic cuticle (Morris 1967, Clegg et. Al 1995). It is in the dense chorionic layer that contains the pathogenic bacteria that enter the feed during incubation.

The final stage of incubation is the separation of the Artemia nauplia from the hard shells and unhatched Artemia cysts. Complete separation is almost impossible, and this is another serious problem for the larvae. The entry of unhatched cysts and empty shells into the water reservoir can damage the digestive tract of the fish, and can also possibly become the cause of death of the fish (Herald and Rackowicz 1951, Morris 1956, Stults 1974).

In addition, even when using  dry Artemia cysts with a high hatching rate (80-90%), you inevitably lose 10-20% of unusable cysts.

The solution to a number of problems associated with the presence of a hard shell is the cysts decapsulation. The hard membrane can be completely removed by various methods, and implies many advantages over the use of dry Artemia cysts. In addition to mitigating the risks of damaging the internal organs of fry and disruption of the gastrointestinal tract, nauplii that are hatched from these decapsulated cysts have a higher energy value, since the embryo requires less energy to "break" through the egg shell (Bruggeman et al. 1980, Vanhaecke and Sorgeloos 1983). As a consequence, the speed and synchronization of nauplia hatching increases, reducing incubation costs.

Decapsulated cysts are also susceptible to disinfection, thereby reducing the bacterial load of the incubation medium (Shelbourne 1964, Gilmour et al. 1975).
The cysts that did not hatch after the incubation are surrounded only by an embryonic cuticle. Compared to the dry Artemia cysts with a similar hatching rate, such cysts represent a completely safe, ready-to-use biomass. Thus, the use of hatchable decapsulated Artemia cysts reduces the incubation waste to zero.

Due to the fact that the Artemia crustacean is a non-selective filtering organism (Campbell et al. 1993; Dixon et al. 1995; Sorgeloos et al. 2001), it is possible to use Artemia to fight diseases in aquaculture through the bioencapsulation of antimicrobial agents, lipids, proteins, probiotics , vitamins, and other medicinal substances. Fortification diets offer more options to meet the needs of different fish species and help reduce disease, stress, malformation and pigmentation problems in many fish species, to support larval growth and survival (Sulistyowati et al 2006; Widiastuti et al 2012; Herawati et al 2014). Several studies have shown the success of probiotics in improving survival and immune response of the shrimp (Nimrat et al 2012; Zokaeifar et al 2012; Widanarni et al 2015), while prebiotics have shown the ability to improve feed digestibility, feed efficiency, microflora composition in the intestine and immune system of shrimp (Li et al 2009; Zhang et al 2012; Aktas et al 2014).

Our new product "Embryo" is hatchable Artemia cysts, cleaned from the outer shell. The innovative formulation and production method provides a high hatching rate of 85-90% and a long shelf life at various temperatures, making it suitable for both hobby aquaristics and production scale. The use of disinfected Artemia nauplii in combination with probiotics ensures the domination of beneficial rather than potentially pathogenic bacterial community. Bioencapsulation technologies used in production open up a wide range of possibilities for delivering the required nutrients and medicine in accordance with the goals set to meet the needs of fish.