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. •T ~•~,l 7 Spawning in a Flow-Through Pond Pond D was prepared by placing two overlapping sheets of pressed fiber- glass cloth, 16 feet wide and 27 feet long, across the shallow end of the pond making a liner about 31 x 27 feet. About six yards of rock ranging from ~" to 4" in diameter was scattered evenly over the liner. The pond was filled to a level that covered the rock area from 8" to 24". A three inch pump was used to wash the rocks as the pond was being drained. The pond was refilled and stocked with five females and five males. The adults were seined nn March 5 or 4$ days after they had been stocked in 5C. The females did not appear to be as gravid as would have been desired and it was questionable if spawning would occur. Circular Tank Spawning • Three ripe females and males were placed in each of two six-foot circu- lar tanks, with a water depth of 22 inches. The females in tank ail were in- jected intraperitoneally with dried carp pituitary at 2 mg/lb body weight. The males were injected with. 800 IU human chorionic gonadotropin per pound of body weight. The females were injected daily for three days whereas the males were injected only once. The fish in tank X12 received no hormone and served as a control. Each tank had about 20 gallons of rock, from to 3" diameter, covering the bottom of the tank. A flow of 10 liters per minute of well water (62±10F) was delivered under pressure and aimed at about a 450 angle to cause a circular flow. Tank (Holding House) Spawning A bed of rocks and gravel 4" deep was placed in the upper one-quarter of each of four (30''. x 24"•' x 10') holding house tanks:' Water was flowed at 15 gmp through the tank. The water was delivered through an outlet that was below the level of rock bed. Each tank was stocked with one pair of razor- - 2