Skin color control of the red sea bream (Pagrus major)

The effect of different concentration of K+ and Na+ on the skin colour of red sea bream and on melanosome movements in melanophores was investigated by using a video microscope system and subsequent image analysis. Soaking in artificial sea water containing 470 mmol/L NaCl, 10 mmol/L KCl, 10 mmol/L CaCl2 and 50 mmol/L MgCl2 failed to prevent skin darkening, while solutions containing over 300 mmol/L KCI instead of the corresponding amount of NaCl induced aggregation of melanosomes, effectively preventing skin darkening. However, soaking in a solution containing 480 mmol/L KCI diminished the red colour of the fish skin. It is concluded that the solution containing 300 mmol/L KCl is useful to maintain skin colour of red sea bream and improve its commercial value. (C) 1998 Academic Press Limited.