LAUSR

To monitor the continuous growth of farmed fry, we present an automated method for measuring the length of free-swimming fry in a small aquarium. The proposed method detects the frame where a swimming fish appears for the measurement in a movie and estimates the locations of its snout and caudal fin base from its shape characteristics. The length is measured as the distance between these two points in 3D space, whose 3D coordinates are obtained by the method of direct linear transformation. The performance of the proposed method was examined by applying it to 10 fish in each of six species, and the standard deviation of the error rates was less than 5%. In the best case, the mean value and standard deviation of the error rates were 6.6 and 1.7%, respectively.