As in the case of relative size, the effect of the number of food patches on the time spent by fish in the bottom patch was revealed only in the presence of crayfish. Under increased competitive pressure and risk in the bottom patch following the introduction of crayfish, the fish decreased their foraging duration in the bottom patch more readily when an alternative food patch was available. However, since intraspecific competition occurred as well, we could expect a similar result also in the absence of crayfish. Furthermore, although overall the fish spent significantly longer time in the upper patch under two-patch conditions, no significant interaction between the number of patches and crayfish presence was found for the upper patch. This indicated that the significant reduction in foraging time in the bottom patch in the presence of crayfish was not accompanied by an increase in the time spent by fish in the upper patch, suggesting that the fish preferred the bottom patch over the upper one. This preference is further supported by the fact that the dominant fish spent longer time in the bottom patch compared to the other fish, assuming that competitive rank should be correlated with percentage of time spent in the better (preferred) patch (Sutherland and Parker, 1992 and Tregenza and Thompson, 1998). A possible explanation may stem from the finding that the reduction in the time spent in the bottom patch was due to shorter time per visit rather than to less visits. That is, instead of allocating more feeding time in the less preferred patch in the presence of crayfish, fish continued to feed in the bottom patch but changed their foraging tactic and snatched pellets from the bottom patch, taking advantage of their quickness relative to the crayfish. The fish persistence in the bottom patch in the lack of an alternative patch induced reduction in feeding time of crayfish in that patch, which was not evident when the food was supplied in two feed patches (Fig. 3).