Recirculation aquaculture system (RAS) is the type of land-based aquaculture production
that interferes the least with the environment, particularly due to low effluent volume
and overall water requirement. Water reuse, sometimes limited by the accumulation of waste
products excreted by fish, can be improved by incorporating another biotechnical component
in the form of high rate algal pond (RAS+HRAP), thus adding to the economy and self
sustainability of the system. Our goal was to evaluate whether rearing fish for 1 year in
a RAS or RAS+HRAP led to differences in fish production and health, by assessing: (1) fish
growth; (2) impact on the morphological structure of sea bass target tissues (liver,
kidney, and spleen); (3) susceptibility to monogenean parasites; (4) resistance to
pathogen challenge with Listonella anguillarum; and (5) total blood
protein. Over the one-year experimental period, sea bass showed no statistical differences
in any parameter evaluated, suggesting that there was a satisfactory purification rate in
the RAS+HRAP system.