In conclusion, the results of the current research indicated
that ORP around 300–320 mV in fish tank had a negative influence on the feed intake, feed conversion rate and growth rate.
Meanwhile considering hematological parameters, it appears as
impossible for seabass to adapt to ORP of 300–320 mV. However
fish under 300–320 mV were less sensible to bacterial infection,
which suggests that a slightly increased and well controlled ORP
level (above 240–270 mV) has a positive effect. Consequently, we
suggest that ORP for seabass in RAS should be elevated but not
exceeding 300 mV. A slight increase of the ORP level in RAS seems to
improve the water quality and the ability of the fish to react against
pathogenic bacteria. Moreover a strict control of the TRO level is
strongly suggested and further studies are necessary to identify
how ORP alters the physiological fish parameters and microbe community in both water and fish.