Sensitivity of tilapia to infrared light measured using a rotating striped drum differs between two strains

Abstract

This experiment was conducted to determine the sensitivity of two different strains of tilapia Oreochromis niloticus (G8 and J1 strains) to infrared light using a rotating striped drum. Two hundred fish (TL 3-4 cm) of each strain were exposed to five wavelengths (visible rays and those over 700, 750, 780, and 800 nm) using filters. All of the fish showed the same sensitivity to visible as well as light over 700 nm. Ten percent of the fish among the G8 strain could sense light over 780 nm. None of the fish in the other strain (J1 strain) could sense light over 750 nm. However, wavelengths over 800 nm did not elicit a response in either strain. It is concluded that 1) a straindifference exist among tilapia with respect to infrared light sensitivity, and 2) at least one strain (G8 strain) of tilapia can sense infrared light in the range of 780-800 nm.