Four replicates were set for the experiment on each regime.
Twenty-four glass aquaria (45 cm×25 cm×3 0 cm, water volume:
35 L) were used for shrimp rearing. Each aquarium held five individuals
and was covered with a 5-mm thick screen (the screen is
laboratory-designed, which is wooden frame sandwiched with transparent
plastic net) to prevent the shrimp from jumping out. The
different light treatments (shaded from each other with black plastic
sheeting) were in one room where temperature was controlled
using an air conditioner. The lamps were hung at 60–80 cm above
the aquaria. The same illumination intensity at the bottom of the
aquaria was realized by adjusting the distance between the lamps
and water surface and the number of light bulbs. The luminance at
the bottom of experimental aquaria was 300±50 microE·m−2·s−1,
which was measured by an underwater illumination photometer
(JD-1A, made in Shanghai Xuelian Instruments Co.).