Assessment ot the environmental safety and effect of human activities, particularly the use of industrial chemicals and pesticides, has become common practice and is regulated in most countries by rules and legislation. The process of safety assessment is primarily dependent on the availability of biological data, which are generated by ecotoxicological research in molecular biomarkers, whole organisms such as fish, daphnia etc., or on populations of organisms such as occurring in nature. Such tests in order to produce reliable results need sophisticated equipment developed and constructed in close collaboration of biologists and engineers specialised in micro-technics and electronic control and monitoring. Changing requirements, biological or legal, induce frequent modifications and hence equipment which can easily be adapted to new situations.