Influence of color and brightness on ontogenetic shelter preference by prawns (Macrobrachium rosenbergii)

The giant river prawn (Macrobrachium rosenbergii), native to rivers and river mouths of different Asian countries, is a heavily widespread species that has been introduced around the world due to its great commercial importance. These prawns are farmed under many different conditions that might translate to a great range of light environments, which impact their behavior and productivity. Here, as a contribution for prawns welfare and economical productivity, we present the first study employing both visual modeling and behavioral data to evaluate ontogenetic changes on color preference of juveniles and adults of M. rosenbergii. For this purpose, we offered ten shelters of different colors to juveniles and adults and registered their preference. Our results showed that the criterion for shelter preference changed with ontogeny, since juveniles chose shelters based on chromaticity (preference for blue), while adults based their decisions on brightness (preference for dark gray). This preference of adults for dark colors is probably associated with a light avoidance behavior. We recommend providing blue shelters for juveniles and dark shelters for adults.