Polyacrylamide gel electrophoresis was used to analyse the distribution of parvalbumin, myosin light chain, and troponin I isoforms in white muscles of larval, juvenile, and adult Chrysichthys auratus (catfish, siluriforms) and to study the kinetics of their synthesis. Parvalbumin isoform PA II was first detected from day 5 post-hatching and was the main "larval" isoform in this species. PA III appeared at the beginning of the juvenile stage but always remained the minor isoform, even in adult fish. Young mature specimens (approximately 12 cm long) displayed the highest total parvalbumin content. Adult-type myosin light chains were detected from day 8. Densitometric analysis confirmed the light-chain distribution typical of fish muscles, with a relatively high amount of LC3 and a low amount of LC1. We evidenced a "larval" form of troponin-I and its progressive replacement by an "adult" form.