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Several male Penucus stylirostris were selected from a 3 ha commercial earthen pond and were individually evaluated for reproductive performance. Indicators measured were compound spermatophore weight, sperm count, and sperm abnormalities. It was found that spermatophore quality was significantly better for 30–40 g shrimp than for 20–30 g shrimp (P < 0.05). The higher frequency of abnormalities measured in younger males and the inverse relationship between abnormalities and sperm count indicate that the vas deferens could be the tissue responsible for producing highly abnormal immature semen. It is proposed that male maturation has at least three independently controlled levels of organization: testes maturation, vas deferens maturation, and spermatophore synthesis. The individual evaluation showed that each male followed a particular response in reproductive quality. Changes in spermatophore weight were not an indicator of sperm density within spermatophores. Male reproductive tract degenerative syndrome (MRTDS) and male reproductive system melanization (MRSM) did not develop in any shrimp during these experiments.