Document Type: Primary Research paper
In this study, given that the tropical long-finned eel Anguilla sp. has colour vision, we determined background colour preference of elvers of this eel in laboratory. The test aquaria covered with a pair of two-colour papers contained with a group of 10 elvers and the position of heads of elvers on each colour background was recorded 15 times for each colour pair. The background colours tested were white, black, yellow, red, green and blue. The frequencies of the head position on each colour of different pairs were analysed by the Thurstone’s law of comparative judgment for paired-preference test. The elvers showed a strong bias for white background, with no significant difference in the mean z-score between the other 5 colour backgrounds. Since no negative impact of white rearing tanks on growth and stress response of other fish species were detected in previous literatures, confinement of the tropical long-finned eel Anguilla sp. in white background was recommended.