One of the most used bioassays for toxicity screening of chemicals and for toxicity monitoring of effluents and contaminated waters is the acute toxicity test performed with Daphnia Magna. Standard methods have been developed and gradually improved by national and international organizations dealing with toxicity testing procedure, in view of its application within a regulatory framework. As for all toxicity tests, the organisms used for the acute Daphnia magna assay have to be obtained from live stocks which are cultured in the laboratory on live food (micro-algae). The technical and biological problems inherent in year-round culturing and the culturing/maintenance costs of live stocks restricts its application to a limited number of highly specialized laboratories. This bottleneck in toxicity testing triggered investigations forward the concept of “microbiotests” or “small-scale” toxicity tests. This paper deals with the measurement of changes in the behavior of Daphniae using device BIOTOXINOMER, awarded by Ministry for Science and Technological Development of Republic Serbia with Diploma for best Innovation idea in year 2010 in category Medicine, Health, and Ecology. Actually, the main topic is digitalization of bio-monitoring results and random number generating on the base of Daphniae movement (distance). The on-line monitoring is available on site www.dundjer.co.rs/Daphniae and open-source software support is available on the same site.