The optimum light colour and intensity of light emitting diodes for catching yellowstripe scads (Selaroides leptolepis) using fixed liftnet

Abstract

The effectiveness of green light emitting diodes (LED) in influencing the behaviour of fish has not been investigated. This study aimed to determine the optimum color and light intensity for catching yellowstripe scads (Selaroides leptolepis) based on their behavioral response and light adaptation. An experiment used two types of LED, blue and green, operated at three levels of light intensity, low (20 lx), medium (35 lx) and high (50 lx). The experiment was conducted in a tank to determine the fish preference zone and pattern of behavioral response to different colors and light intensities. Their retinal adaptations were investigated histologically. For all colours and light intensities, the schooling fish was located mainly in the bright zone (67%). The cone index and swimming speed of fish were slightly increased by intensity. The highest light adaptation was found on blue LED exposure at a light intensity of 88.70%. When being exposed to the green LED, the fish gradually swam closely to each other and formed a stable schooling formation. However, when being exposed to the blue LED, the fish keep swimming widely and randomly. The green LED was an excellent fishing lamp for controlling behavior and harvesting yellowstripe scad in liftnet fishing.