Abstract—This paper presents a simple method of counting
feeder fish automatically using image processing techniques. A
video of a school of fish is taken and every frame is processed
singly and independently. The first step is to obtain blobs
marking the positions of the fish. Several ways of
accomplishing this task are discussed. Noise and background
objects are filtered from the image of the blobs. Area
information of the blobs is used to count the number of fish in
one frame, and the average number of fish over all frames is
then recorded. Experimental results show that the correct
number of fish can be obtained for a school of 5, 10, 15, and 50
fish. Errors within frames increase with the number of fish,
mainly resulting from the fact that area thresholding can be
quite sensitive. Finally, a discussion about the method’s
effectiveness and possible improvements are provided.