Carnivorous fish such as the sea bream normally rely heavily on gluconeogenesis from
protein to fulfil its energy demands (Cowey and Sargent, 1979; Hepher, 1988).
In sea bream cultured in an iso-osmotic medium, there is evidence that gluconeogensis is suppressed (reduction in hepatic G6Pase activity) but glycolysis is stimulated (enhancement
of hepatic hexokinase activity).
These phenomena, coupled with a reduction in ammonia excretion rate, would indicate that in an iso-osmotic environment, metabolism is re-organised in a way that would allow protein sparing in favour of a shift towards preferential carbohydrate utilization.
Liver lipid levels of the 15 p.p.t. groups were significantly lower than the corresponding groups at 7 p.p.t_ and 35 p.p.t. This would indicate that increased lipid utilisation is also prevalent at 15 p.p.t