Tidally-controlled river plumes form distinct frontal boundaries that can change the spatial distributions of larval fishes and their planktonic prey and predators. Ephemeral in nature, they may expose larval fishes to varying trophic environments over small spatial and temporal scales, with unknown consequences for survival and recruitment. In the northern California Current (NCC), the Columbia River plume (CRP) is an important habitat for larval marine fishes, strongly influenced by twice-daily freshwater injections that create a highly dynamic coastal environment. We used the In situ Ichthyoplankton Imaging System (ISIIS) to examine changes in the fine-scale horizontal and vertical distribution of larval fishes, their prey, and their predators over space (inshore/offshore) and time (ebb/flood tide). During summer 2016, 6095 fish larvae and nearly 1.5 M prey and predator zooplankton were imaged. We observed strong taxon-specific distributions, but all taxa occurred primarily below and not within fresher plume waters. Fish larvae and their prey were generally distributed deeper in the water column than their predators. However, the presence of a shallow horizontal front reduced the magnitude of this difference, contributing to a high spatial overlap of larval fishes with their prey and predators. This co-occurrence of larvae with their predators was taxon-specific and varied with the tide and depth of the horizontal front. Notably, high zooplankton concentration did not necessarily confer spatial overlap on small scales (meters in the vertical, kms in the horizontal) relevant to trophic interactions. Our results suggest that in the vicinity of river plumes, larval fishes likely experience a diversity of unique prey and predator fields over short spatio-temporal scales.