Pomatoschistus microps is 1 of the most common fish species inhabiting Mediterranean coastal lagoons. This small species uses an early maturation and a short life span to occupy sites subject to high variability in environmental factors. During monthly investigations on a P. microps population of the Vaccarès Lagoon from March 1993 to December 1997, 2 conspicuous parasites were noticed. The digenean Aphalloides cœlomicola was harbored in the abdominal cavity of the fish, whereas the myxosporean Kudoa camarguensis was found in the muscle tissues. Monthly peaks of prevalence occurred at the same period for both parasites, and a positive correlation (permutation test and Janson and Vegelius correlation) was observed between their occurrences among sampled fish. These results suggest that this positive association is related to a third common factor, i.e., their host's life cycle.