Brine shrimp (Artemia salina).
Artemia (Artemia salina). Artemia belongs to the class Crustacea, subclass Branchiopoda, order Anostraca, family Arterniidae, and genus Artemia. Artemia inhabits chloride, sulfate, and carbonate waters with salinity reaching up to 300 ppt. However, it can live in freshwater for some time, allowing it to be used as live food for freshwater aquarium fish. The main habitats in Ukraine are the Odesa and Crimean estuaries; it is also found in saline lakes of other regions. In southern areas, relatively large brine shrimp reaching 8-11 mm are widespread in saltwater bodies.
The coloration varies from greenish to bright red depending on the food consumed and the concentration of oxygen dissolved in the water. Unlike cyclops, they have a soft outer covering, making them suitable for all fish species. The egg sac in females is located on the abdomen. Average fecundity is 50-60 (max. up to 250) eggs, with broods every 5-7 days, totaling 15-18 times in a lifetime. Juveniles reach sexual maturity in 18-30 days. Under conditions that prevent hemoglobin formation and with a lack of chlorophyll in the diet, Artemia becomes viviparous. Artemia lives for up to 6 months.
In nature, the main food of the shrimp is the microalga Dunaliella salina. It contains up to 7.2 mcg of vitamin B12 per 1 g. Artemia contains a large amount of hemoglobin, as indicated by the red color of its nauplii and adult shrimp. Artemia nauplii contain over 50% protein and more than 23% fat. Artemia is perhaps the only fish food that can be successfully bred (cultivated) at home with little effort—all you need are Artemia eggs (cysts), a suitable container (jar) with water, an air pump with an airstone, and table salt. Artemia juveniles are an excellent food for fry and small fish species. When bred at home, hatched nauplii can be grown on to feed adult aquarium fish.
The hatch rate heavily depends on the specific batch. For a good hatch of nauplii, it is best to use relatively fresh eggs stored for no more than 5 years, preferably 2-3 years. Artemia eggs must be stored in airtight packaging in a dark, cool place. In plastic bags, Artemia can be stored in the bottom compartment of a refrigerator. Ideally, up to 95% of the shrimp can hatch, but 40% can also be considered a normal result. Nauplii and decapsulated Artemia eggs often contain Salmonella bacteria, which cause digestive tract enteritis and liver damage in fish.
To kill Salmonella bacteria often contained in Artemia eggs, they must be kept in a refrigerator at a temperature of 2-5 degrees. Dried cysts should be stored in moisture-proof packaging. Despite high resilience, improper storage of cysts can lead to the death of embryos. Cysts are very hygroscopic and absorb moisture in the open air, leading to increased internal metabolic processes and, consequently, the depletion of energy resources.
There are several express methods to quickly determine the quality of cysts. Here are some of them. Cysts are rubbed between fingers. In a dry state, dead cysts and shells 
crumble into powder, while when wet, they roll into “spindles,” whereas live ones remain as grains. You can place cysts between thin glass slides and, after crushing them, examine them under a magnifying glass. Fat spots form around live ones. Another method is treatment with sodium hypochlorite. After 5 minutes, the cyst shell dissolves, and live orange embryos become visible. Thus, using a small number of cysts, you can roughly determine the hatching percentage of the available Artemia eggs.
The cyst shell is multi-layered. Under a thin surface membrane lies the chorion, a hard dark brown spherical shell. Its main function is to protect the embryo from mechanical damage and ultraviolet solar radiation. The chorion is not destroyed by fish digestive enzymes, so a swallowed cyst passes through the intestine undigested. However, the chorion can be dissolved using products containing active chlorine: chlorine dioxide, sodium or calcium hypochlorite, or bleaching powder. This procedure is called decapsulation: the embryo is stripped of its protective shell while remaining alive. Decapsulated eggs tend to clump together more easily.
Such eggs (precisely because they lack a shell) are much more demanding regarding storage conditions. This food can be stored for a long time in a dry, cool place in a tightly closed jar. Decapsulated (shell-free) cysts can be fed directly to larvae or incubated in the usual way. Incubating decapsulated cysts has its advantages: • there is no need to separate shells and undeveloped cysts from nauplii, as they do not enter the incubator; • the possibility of introducing bacteria dangerous to fish into the aquarium disappears; • newborn nauplii are more nutritious because they do not expend energy on breaking the shell and emerging from it; • the hatch rate of cysts doubles; • the survival rate of fish fry fed with decapsulated Artemia almost doubles.
It is especially valuable that artificial breeding of Artemia completely eliminates the introduction of various diseases into the aquarium. Decapsulated rinsed cysts can be fed immediately to fish or preserved. Feeding with decapsulated Artemia should be strictly dosed, preferably in several stages. Since decapsulated Artemia is artificially stripped of its chitinous shell using special preparations, and it is very difficult to determine the quality of an individual cyst by eye, portion control should be decisive and reasonable, and the use of this type of food should not be regular. This food usually sinks to the bottom of the aquarium, and if left uneaten, it must be removed immediately.
If necessary, larvae are grown on by feeding them yeast cells (0.2 million/ml) or microalgae (1 million cells per 1 ml). After 5-7 days, the grown Artemia can be fed to medium-sized fish. For preservation, they are placed in a saturated sodium chloride solution at room temperature. Within 3-4 hours, the cysts are dehydrated (with stirring or aeration), after which they are strained and placed in a fresh saturated sodium chloride solution. In this form, they can be stored for up to two months in a freezer at temperatures below minus 4°C. As needed, cysts are removed from the solution, rinsed, and fed to fish or subjected to incubation.
Decapsulation of Artemia eggs.
Non-decapsulated eggs must be activated before incubation. Before starting incubation, eggs are removed from the freezer and left for 3-4 days at room temperature. Before incubation, cysts can be treated to break diapause and increase hatch rates. Cysts are decapsulated after one hour of hydration. Here are a few methods.
• Freezing: The best results are obtained by keeping cysts in a saturated saline solution for 1-2 months in a refrigerator freezer (at minus 25°C).
• Hydrogen peroxide treatment: 50 grams of dry cysts are kept for 30 minutes in 1 liter of a 1.5-3% hydrogen peroxide solution, followed by drying before incubation. Hydrogen peroxide can also be added directly to the incubation apparatus. Part of the eggs can be dried and stored for several days for batch feeding.
• Freshwater and salt treatment: Dry cysts are soaked in freshwater at 25-30°C for two hours. Then they are strained and kept for a day in a saturated salt solution. This procedure is repeated three times, after which the cysts are incubated. Purified iodinated salt should not be used. It is better to perform double activation—first with cold: dry eggs are poured with a saline solution (50 g/l) and frozen in the freezer for 7-10 days, which increases the hatch yield. Even a single day in the refrigerator freezer shortly before incubation can increase the yield of shrimp. If you are planning spawning, it is better to freeze Artemia longer—a couple of weeks or months.
• A mixture in which 30 grams of calcium hypochlorite and 16 grams of anhydrous sodium carbonate are successively dissolved in 1 liter of water is very effective. The ratio of eggs to solution is 1:10. The components are thoroughly mixed for 1-1.5 minutes. After dissolution, the mixture is left to settle for 15 minutes, and the liquid is decanted from the sediment.
To destroy the egg shells after freezing or 1 hour of hydration in water, having strained the water, they are placed for 20-30 minutes in a solution of: • 3% calcium hypochlorite; • 5-6% bleaching powder; • 9% sodium hypochlorite; • They can be activated with borax, soda, or acetone.
The volume ratio of hydrated cysts to solution is 1:5. Decapsulation lasts up to 1 hour with constant manual stirring of the cysts or aeration from a compressor. The dissolution of the chorion is easily controlled visually: the initial brown color becomes whitish and then turns orange. You need to wait for the decapsulation of all cysts, after which they are rinsed with running water to remove residual chlorine. The rinsing process can be accelerated by immersing the cysts in a sodium thiosulfate or sodium sulfite solution. All filtering devices must be made of nylon and other chlorine-resistant materials (polyvinyl chloride, polystyrene, unplasticized PVC, rubber, glass, porcelain).
Methods of breeding Artemia. Artemia incubator.
Live food for feeding aquarium fish. 
