2.2.3. Statistical analysisMixed effects ANOVA was conducted to compare the effect of light stimulus on the distribution of each fish species in the cage. Here, the effect of light was considered as fixed effect and the effect of echo traces that have auto correlation structure was considered as random effect. The linear mixed model analysis was made using the lmer function of the package lme4 in the statistical software R ver.3.4.3. Following models were fitted to data sets of each trial:Distance ˜ Species + (1|Trace)where Distance is the echo distances from the base side, Species is the fixed effect of 4 levels (Control, BET, SKJ and Unid) and the term(1|Trace) is the random effect of echo traces.If mixed effect ANOVA test was significant, post hoc Tukey HSD were made to compare the effect of light on three species(BET, SKJ and Unid) to the control. The analysis was made using glht function of package multcomp in R.