Light spectrum effects on giant freshwater prawns, Macrobrachium rosenbergii: Larval development, survival and preferences

The objective of this study was to evaluate the influence of different light spectra on growth, development indices, survival and color preferences in Macrobrachium rosenbergii larvae. First (trial 1, 25 days), prawns (100 larvae/L) were randomly allocated to 30 cylindrical plastic containers (1 L). This trial was designed with five treatments (light spectra) and six replications: red light, blue light, green light and white light or absence of light (controls) in the 12:12 light:dark (LD) cycle. Next (trial 2), 30 groups of five larvae in two different development stages (VII and XI) were allocated to a system of compartments with different lights: white, red, blue or green. This system was connected by tubes to enable light spectra choices. Final weight, weight gain, consumption and metamorphosis significantly improved under the white light condition versus the other tested groups (p<0.05). Survival, the Larval Stage Index, the Larval Condition Index and final biomass clearly improved under the white light condition (p<0.05). Conversely, the red light and no light conditions obtained unsatisfactory results. White light was preferred in larvae stage VII (p<0.05), but this behavior changed to blue when prawns reached life stage XI (p<0.05). These findings suggest that white light may be the best choice to optimize larval growth and survival, while color preferences may vary with development stage. • Dark light environment can negatively affect in M. rosenbergii larval development. • Behavioral preferences of light spectrum can change acoordeing to life stage. • The white light promoter graqter survival of M. rosenbergii larvae.