The effects of nicotine (NIC), 6-hydroxy-L-nicotine (6HLN), and cotinine (COT) (1 and 2 mg/L) administration in scopolamine (SCOP)-treated zebrafish on spatial memory and locomotor activity evaluated within the Y-maze task. (A) The representative locomotion tracking pattern of the zebrafish in the second stage of the Y-maze task according to the experimental groups they belong to. The arms of the maze were denoted with A (start arm), B (other arm), and C (novel arm). The blue dot represents the beginning of the route, while the red dot represents the end of the route. The time in the novel arm (B) represents a parameter for spatial memory, whereas the (C) total distance travelled and the (D) turn angle is measures of locomotor activity. The values are expressed as means ± S.E.M. (n = 10). ANOVA analysis identified overall significant differences between the experimental groups for (B) F(8,81) = 10.54, p < 0.0001, (C) F(8,81) = 5.342, p < 0.0001 and (D) F(8,81) = 8.96, p < 0.0001. For Tukey posthoc analyses—**** p < 0.0001, *** p < 0.001, ** p < 0.01and * p < 0.05.