Grey gurnards (Eutrigla gurnardus) belong to the family of triglids. They are demersal, widely distributed fishes in the North Sea, ranked among the most dominant species. Triglids are known to produce sounds by drumming sonic muscles against their swimbladder. Analyses concerning differences between acoustical activity of groups and single fish were made by event-based recording of audio and video. Experiments were conducted in a two by two meter tank with a water level of 46 centimeters. Acoustical behavior of three different conditions was analyzed for periods of 48 hours. Compared were groups of five fish with single fish and with a group of four dummies and a single fish. Additional focus lay on determination of acoustic composition and a possible influence of the experimental tank. Recordings and analyses were conducted computer-based with software particularly configured for research on acoustical behavior of fish. Corrections and changes concerning experimental set-up recommended by previous work were considered. Improvement of tank acoustics could be found. In 108 days of recording a total of 4957 fish sounds were found that split up into five different categories: Knock, Grunt, Growl, Knock-train and a new category: Croak. Croaks were not described in any literature before. They seem to be very rare, since a total of only 20 sounds were found. All categories were described in detail. Results showed a high variance in acoustical activity in all experimental parts and an influence of water temperature and length of light period on sound generation. A significant difference was found between groups and single individuals concerning acoustical activity and -composition. The effect of dummies as replacement of group members was not explicit because of high variances in sound production. Received data showed a high potential for further investigation. Possible improvements were recommended.