Abstract: | During the last few decades several fish feeding methods and techniques have been developed in part as a result of intense aquaculturing and increases in fish demands on the global market and in part for comparative studies to test the influence of certain feeding techniques on fish growth, feed efficiency and feed wastage (Pfeffer 1977, Thorpe et al. 1990, Alanärä 1992a, Kentouri et al. 1993, Paspatis et al. 1999).Generally 3 categories of feeding system or techniques are recognized: hand-feeding, fixed feed ration systems and demand feeding systems. In practice, the choice of feeding system or technique must be made following considerations of type and level of production and the cost of the feeding system. It may be necessary to change different feeding techniques during the production cycle and several techniques may be combined.Hand-feeding is the oldest and most simple feeding technique but it can be very efficient as the farmer has daily contact with the fish and it is possible to make direct observation on the individuals and, thus, a more efficient food distribution can be made. From the point of view of large scale commercial production hand feeding can not be considered a viable option due to high labour costs and as it is a time consuming practice.Electronically operated timer-controlled feeding systems appeared and became popular during the 1970s as a result of intensive fish farming, but were replaced by computer based control units at the end of the 1980s, which offered more options for the regulation and timing of feed delivery. Although the price for purchasing such a device is high, the operational costs are low. When timer or computer-controlled systems are used, the quantities of feed to be supplied are determined on the basis of either feed tables or mathematical models describing daily energy requirements. Demand feeding systems were developed during the 1980s and 1990s for use on commercial farms and are based on the principle that the supply of feed is regulated by the demand of the fish. Demand feeders work in one of the two ways: either by fish requesting feed themselves (self-feeders) or by automatic cessation or reduction of feed delivery when feeding activity declines (interactive feedback systems). |
