Figure 1.

Open field and novel tank diving test setups and representative results of tracks and heatmaps over different ages. Experimental setup for the open field (A,B) and novel tank diving test (E,F). Tracks and heatmaps show differences in open field behavior with age, where aged fish spend more time in the center (C,D). The size of the center zone was adjusted to the size (age) of the fish. (G,H) Example tracks and heatmaps for the novel tank diving test for 6-week and 18-week-old fish. (I) Representative images of 6-, 12-, 18-, and 24-week-old fish. The arrowheads indicate spinal curvature which is visible from 12 weeks and the lip protrusion, which is visible from 18 weeks.