Significantly higher glucokinase (GK) activities were observed at 2 h than 24 h postprandial except in the cellulose group. At 2 h postprandial, significantly higher GK activity was observed in fish fed with the dextrin diet than those fed with the cellulose diet. Dietary carbohydrate source did not affect GK activity at 24 h postprandial (Fig. 2). Pyruvate kinase (PK) activity showed a similar trend with GK activity, except for fish fed with maltose diet which showed significantly higher PK activity than fish fed with the cellulose diet (Fig. 3).