Opera house traps are the most popular gear used to catch the oriental river prawns in the Anzali Lagoon, Iran. In this study, the effect of two kinds of baits attached to opera house traps was subjected to an evaluation from April to September 2015 in the Anzali Lagoon. The opera house trap was designed for catching the oriental river prawns. A total of 20 opera house traps were randomly set along the shoreline at intervals of approximately 3 m. Ten traps were set baited by bread, and ten traps were set baited by fish. Results showed that the mean catch per unit effort (CPUE) was significantly different between the two different baits (P < 0.05). The maximum CPUE was recorded in July (22.95)  with bread bait.  During the period time of each treatment, the CPUE did not show any significant difference (P > 0.05). In addition, the length-frequency distributions of M. nipponense in opera house traps, baited with fish and bread, showed no significant difference (P < 0.05). Therefore, there was no difference between bread and fish baits of any size for absorbing the prawn. Results showed that, due to most factors affecting the CPUE of M. nipponense, bread proved to be a better bait selection.