We examined how channel system order and complexity influence fish community composition, abundance, and diet, by comparing first-through fourth-order channel systems at China Camp Marsh, San Francisco Estuary, California, USA. We sampled 6 channel systems (with replicates of the second-and fourth-order systems) bimonthly from July 2001 to May 2002 using modified fyke nets. We examined the diet of the 3 most common species that occurred consistently over time (seasonally): Atherinops affinis,

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... nidia beryllina, and Leptocottus armatus. Low-order (first-and second-order) systems supported higher densities of Gambusia affinis and Lucania parva. High-order (third-and fourth-order) systems supported greater species richness and densities of juveniles, including Clupea pallasi, than low-order systems. Prey taxa richness was greater for M. beryllina and lower for L. armatus in the first-order system. There was a positive correlation between high-order channel systems and mean stomach fullness scores for L. armatus, and M. beryllina had greater short-term consumption rates in high-order channel systems. Habitat heterogeneity, and specifically the presence of both low-and high-order channel systems, is necessary to accommodate early life stages, species-specific dietary requirements, and enhanced species richness of fishes at China Camp Marsh. Based on our results, we recommend that the processes and landscape scales that promote channel formation be considered in future salt marsh restoration projects. KEY WORDS: Channel system order · Tidal marsh · Fish ecology · Community composition · Diet · Wetland restoration Resale or republication not permitted without written consent of the publisher