A new method of automatically counting fish using an artificial neural
network is presented. A back propagation of error feed-forward neural
network has been trained to count synthetic fish populations. Trained
networks are subsequently shown to generalise well to previously unse
en fish tank scenes, giving a 94% success rate on scenes containing up
to 100 fish in a variety of orientations and overlaps. This out-perfo
rms both pixel counting and energy estimation methods.