Some effects of supplemental feed and fertilizer upon production of red swamp crawfish, Procambarus clarki, were measured during a five-month period at Baton Rouge, Louisiana. The tests, in vinyl-lined pools and earthen ponds, also evaluated stocking rates of 10,000 and 20,000 young per acre, effect of artificial cover on survival of young, and necessity of soil as substrate in crawfish production. The influence of feed, fertilizer, and soil on total hardness of well water was studied. The relationhip of total hardness of water to survival and growth of young crawfish was observed. Survival of crawfish in pools with soil was: fed, 65 percent; fertilized, 56 percent; control, 78 percent. In pools with no soil, survival was: fed, 0 percent; fertilized, 32 percent; control, 0 percent. Survival in pools was apparently not affected by increasing the stocking rate from 10,000 to 20,000 per acre, or by adding artificial cover. Average net production in pools with soil ranged from 90 to 372 pounds per acre. Feeding significantly increased produotion, but fertilization did not. Average net production in earthen ponds ranged from 107 to 251 pounds per acre. No significant increase was shown by feeding or fertilization, but many fed crawfish had matured and burrowed by draining time. Total hardness of well water in pools was increased from approximately 6 ppm in controls to 7 ppm by feeding, to 17 ppm by fertilizing, and to 65 ppm by adding soil. Well water added to earthen ponds developed a total hardness similar to that of pools with soil. Survival and growth of young crawfish in pools was minimal at a total hardness of approximately 17 ppm, and best near 65 ppm. Sex ratio of pool-reared crawfish was 1 male: 1.25 female. Sex ratio of pond-reared crawfish was 1.08 males: 1 female.