Four types of traps were designed and tested monthly during 1997 in the field for effectiveness in crayfish catchability. Trap with one entrance and 3.0 cm mesh size of its netting cover was found to be the best type that can catch large marketable sizes of Procambarus clarkii (≥ 10 cm total length). The effect of trap density, bait type, habitat type, time interval sets, water quality on the effeciency of this trap type were also studied. The obtained results indicated that the highest catchability of the chosen trap type was obtained when four traps /100 m2 were used twice daily, each for six hours, baited with frozen fish and put in muddy shallow sites with high vegetation. Also catch per unit effort of this trap model was found to be positively correlated with water temperature, pH, water transparency and density of zooplankton and benthos and it was also affected by the rate of dissolved oxygen.