Young shrimp have shown rapid growth in brackish-water ponds which had been fertilized, but to which no supplemental feed was added. In 1966, white shrimp (Penaeus setiferus) were stocked at the rate of nine shrimp per square meter of bottom in a pond that had been fertilized with chicken manure. In 1967, brown shrimp (P. a. aztecus) were stocked at a rate of 22 shrimp per square meter of bottom in one pond that was fertilized with rice husks and in another that was not fertilized. In both experiments initial growth was rapid; the shrimp attained bait size (75 to 93 mm total length) in 5 to 7 weeks. This rapid growth was followed by a period of slow growth. In 1967, supplementary feeding produced additional gains after growth had nearly ceased. Survival of the white shrimp was 84 percent, whereas survival of the brown shrimp was 23 percent in the untreated pond and 31 percent in the fertilized pond. Oxygen deficiencies caused by dense blooms of phytoplankton during the 1967 experiment resulted in serveral mass mortalities.