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FISH FARMING TECHNOLOGY by Martin Hochleithner, AquaTech, Austria

Wild-caught zooplankton, mainly copepods and phyllopods, which make up over 90 percent of total zooplankton biomass in lakes and seas, is the optimal food for fry and fingerlings up to a size of 3-5cm. It serves as initial feed for the production of sensitive and valuable fish stocks of species such as char, grayling, whitefish, eel, sturgeon, bass, bream, and numerous others

THE INFLUENCE OF AN AUTOMATIC FEEDING DEVICE FOR FROZEN ZOOPLANKTON AquaTech (Aquaculture Technology) is the name of an Austrian company that produces and supplies innovative and efficient technology for use in aquaculture. Products developed initially in Austria are well known and used worldwide, like the older clockwork-belt feeder or the newer solar-feeders. At the vanguard of aquaculture development, Austria has a long tradition in the successful use of live zooplankton caught from natural waters as starter feed for various fish larvae raised in tanks (Einsele, 1949). Less known are the recent Austrian developments for harvesting and grading of zooplankton, for example a multi-sieve plankton-net (Steiner & Hochleithner, 2016). Another such innovative and unique product is an automatic feeder for the professional controlled administration of frozen zooplankton in hatcheries or nurseries. This patented “Planktonfeeder”, developed at the “Institute for Fish Research” in Austria, is available in its third generation. It has dimensions (L x W x H) of about 79 x 49 x 73 cm and can accommodate in two compartments up to 20kg of frozen zooplankton. The feeding technique is based on an electronic controlled process, which “washes” the plankton layers off larger-sized frozen pieces and distributes the rations evenly via two specially designed, self-cleaning systems of up to 16 outlet valves. If Y-shaped adapters are used, the unit can even supply up to 32 tanks with plankton. The “washing” and defrosting of the plankton layers achieved by spraying or flooding with water, and the remaining plankton is then re-frozen. In order to avoid the crushing or damaging of the defrosted fragile plankton organisms, distribution to the nursery tanks is carried out along with water current in flexible tubes. Wild-caught zooplankton, mainly copepods and phyllopods, which make up over 90 percent of total zooplankton biomass in lakes and seas, is the optimal food for fry and fingerlings up to a size of 3-5cm (Hochleithner, 2001). It serves as initial feed for the production of sensitive and valuable fish stocks of species such as char, grayling, whitefish, eel, sturgeon, bass, bream, and numerous others (Steiner, 1989).

Studies

The “Planktonfeeder” has been tested and approved with various fresh and seawater species, including fish and shrimp (Steiner, 1989). The following results are from case studies made in two different Austrian fish farms in rectangular and circular tanks with spring and well water (Steiner & Hochleithner, 2016). 38 | April 2017 - International Aquafeed

APR 2017 - International Aquafeed magazine