The present invention provides for the improved uptake of feed additives, pigments for use in coloring the flesh and the like. This improved intestinal uptake of foodstuffs and additives is effected through enhancing the development of the intestinal tract. Specifically the present method comprises of feeding fish with a diet which has an augmented level of nucleotides present therein. The nucleotides may be selected from the group consisting of nucleotides of uridine, guanosine, cytidine, thymindine, adenosine and mixtures thereof. The resultant improvement in the development of the intestinal tract leads to an improvement of the intestinal surfaces to absorb nutrients and/or dietary additives, this increase being at least partly due to an increase in gut surface area, for example through an increase in villus height.