Abstract: An apparatus for monitoring a water quality by raising an aquatic living thing in a monitoring water tank 1. The monitoring water tank 1 is taken through a camera 12 to be displayed on a television 14. A monitoring area E comprising a plurality of sensor points is set on a television scene through a light pen, and a fish sensing device 13 senses variation of the sensor points in luminance level to continuously detect the moving positions of fish F, F' under observation. A personal computer 15 detects, on the basis of the moving positions of the fish under observation, whether or not each of the fish under observation takes any one of a plurality of abnormal action patterns, and conducts an alarm operation if both the two fish F, F' under observation assume any abnormal action pattern.

Abstract: A water quality monitoring apparatus including a raw water supply and discharge unit 7 equipped with a monitoring water tank 5 for breeding fish under observation. The raw water supply and discharge unit 7 is detachably placed in a lower section of a rack 1, and a video camera 8 is provided in opposed relation to the monitoring water tank 5. Also included are a fish detecting sensor 10 for detecting an actional pattern or the like of the fish under observation on the basis of a picture from the video camera 8 and a computer 11 for detecting the abnormality of the water quality on the basis of the detection result of the fish actional pattern or the like. The raw water supply and discharge unit 7 is made to be drawn from the rack 1 lower section, for example, at the time of cleaning its tanks. Thus, the maintenance thereof becomes easily possible, besides the entire apparatus becomes reducible in dimension to make the space necessary for the installation smaller.

Abstract: A television-camera is used to obtain a video image of an area to be monitored, the video image being displayed on the display screen of a television receiver. A light pin is used to set plural display points on the display screen so as to define a specific area within the video image. By comparing density levels of successive frames of the video image, a moving object is detected. An alarm is generated if a detected moving object contacts a set number of the display points set using the light pin. Also, by employing two or more television-cameras oriented at different angles with respect to the area to be monitored, and by setting respective sets of display points for each the thus obtained video images, reliability of the alarm detection can be enhanced.