Growth and maturation of Penaeus indicus under blue and green light

Abstract

The effect of light quality on the maturation, condition and growth of the penaeid prawn Penaeus indicus was tested by comparing dim green and blue illumination against that of diffuse natural light as a control. Initially growth and condition were depressed in all three tanks and this could be regarded as a ‘settling down’ period, while spawning activity decreased in the blue and green tanks, but increased in the control tank. After three to five months the growth slopes became positive under green and blue light and condition improved, though the spawning levels still remained low (consolidation phase). Spawning and condition then continued to improve with time. It appeared that once growth and condition had normalized under blue and green light, spawning activity resumed. In the control, however, both prawn condition and subsequent spawning activity declined steadily after the end of the second month and this could be explained as a final reproductive effort with decreasing condition until the condition was too low for effective spawning. Growth and maturation in P. indicus can thus occur simultaneously without adversely affecting prawn condition provided that both a good diet and good quality light are supplied.