siamese betta fish ukThe results in part parallel a previous study during this species that had demonstrated superior aggression in a fighter strain as in comparison with a wild type strain . However, in that study alterations were evident only during conspecific presentations “mutual viewing test” and not when aggression was elicited by a combination of mirror images and video playbacks of conspecifics. Because the responses to reflect images and video playbacks, which want to be properly validated , were combined, a direct assessment with the effects that we have obtained for the mirror test is not feasible. Also, an identical study in comparison ameliorations between lines using aggression scores derived from a valuable component analysis PCA and not individual behaviours, additional limiting an immediate assessment with our results. Still, the fact that both experiences, which used various lines of wild type and fighter animals, concluded for a much better aggressiveness of opponents, in accordance with our preliminary prediction, strongly imply that adjustments among traces are the results of the choice manner for winning and not of alternative uncontrolled elements. It can be highlighted that the alternative criteria used by breeders is winning/losing and never the frequency/depth of aggressive displays during the staged paired fights.