A fish is living with an excellent color sense and changes of color and environment have been shown to influence the feeding behavior and growth in fish.
As previous report (vol.5), the wavelength of green light can be controlled for its influence in regulating immune systems, accelerating melatonin output of hormones and for alleviating stress in fish. By regulating the light wavelength, we can control the growth rate of cultured species and adopt various fish species and new techniques accordingly.
A green light may generally stimulate growth of fish at low water temperature. Moreover, it is conceivable that a body growth of which is stimulated by green light and it augments food intake, which is intimately coupled with somatic growth.
Recently, a fish under the green LED lighting (54.03%) showed the highest weight rate, followed by the white (38.47%), red (36.98%), and blue LED lighting (34.72%) in these experiments 4 different kinds (Red 645nm, Green 525nm, Blue 465nm, white light) of LED lighting and a fish under the green LED lighting showed the highest length rate, followed by the white, red, and blue LED lighting. Based on these results, a green light provides a suitable breeding environment for the fish. (fig.1)
Fig.1. the change of fish activity by green LED
In fish, there is a light receptive organ called pineal body in addition to sight as a sensory organ for light, so it reacts very sensitively to light. These light stimuli are transmitted to the hypothalamus and affect various physiological mechanisms. In particular, the use of green wavelength light to promote fish growth is an essential biological process and can be an indicator of fish food intake, homeostasis, metabolic regulation, and environmental stress.
Jae Ho Lee, Ph.D
* Next week’s topic : Light and Plants (UV and Compounds)