Locomotor activity (% of the one hour) of armoured catfish Pterygoplichthys spp. juveniles from Am Chua canal. Numbers on the top of the graph indicate illumination of the time periods. Gray color column indicates significant differences (Mann–Whitney U test (5 vs 6; 6 vs 7; 16 vs 17; 17 vs 18 and 18 vs 19): p = 0.0020; p < 0.0001; p < 0.0001; p < 0.0001 and p = 0.0067, n = 55) with the previous column. Standard error (|).