VIRTUAL TOUR - FRESHWATER FARM

Eggs in the final stage of swelling are put into an incubation installation. Salmonid eggs should be incubated in trays with horizontal water flow; eggs of coregonids, pike and many cyprinids can be incubated in Weiss jars. At the moment, the incubation room in the Czarci Jar contains 230 Californian incubators and 20 Weiss jars. Incubation temperatures are dependent on the species in question. Temperatures outside of the species range, increases the chances of egg mortality. Constant water flow, good water quality and appropriate temperature are required for successful egg incubation. Also, the water used in the hatchery must be well oxygenated and clean to enable successful egg incubation.

Salmonid eggs need to be washed when at the eyed stage. Washing, cleans the eggs and incubator of mud and wastes, and also causes breaking of the yolk envelope in unfertilised eggs, so they can be easily separated from live eggs. Eggs are siphoned from the incubators to a plastic bucket with a rubber hose. The bucket has an opening with a net below the upper edge, so that water can flow out while the eggs remain inside. Washed eggs are put back into clean jars. Some of the eggs die in the course of the incubation. Dead trout eggs, which are relatively big, can be removed with a pipette or tweezers. In the case of smaller eggs or a large production, the dead eggs are removed by desalting. The desalting process is carried out when the live eggs have already reached the eyed stage and are more resistant to handling. The eggs need to be transferred to a bucket filled with 9% Sodium Chloride (NaCl) solution. Dead eggs float to the surface, while live ones remain at the bottom. Dead eggs are gently poured out, and the live eggs are removed from the bucket, and placed once again in the incubator. Incubation time from egg fertilization to larvae hatching depends on the fish species and the water temperature.