At the conclusion of the experiment, each fish was weighed again, as
described, and was photographed against graph paper to provide a
scaled, high resolution image. Using Image Pro Discovery software, the
total length of each individual fish was determined to ±0.1 mm by
adding the measurements of the length from the anterior point of the mouth to a point on the caudal peduncle and the length from that point
to the end of the caudal fin. This procedure circumvented bias in the
measurement of fish length due to curvature of the caudal fins at the
time of the photo because fish were not anaesthetised.