The sporadic differences among mean plasma ion concentrations did not show
consistent trends (Table I). One large difference among the ion data is the strong
ion difference. When the chloride (anion) data are subtracted from the total
cation concentrations the resulting difference is 10·5 mEq l"1 for the seawater
fish and 64·5 and 67·74 mEq l"1 for the fresh water and hypersaline seawater
fish, respectively. If it is assumed that the difference is made up by fixed ion
charges (such as on proteins) and bicarbonate ions, and that such fixed charges
were constant in all groups, then these data suggest that the extracellular fluids
of the fish in sea water were more acidic compared to the other two groups