The incorporation of fish into the diet of hunter-gatherers can be evaluated on the basis of their densities, the abundance of high-ranked resources and available technology. This paper examines the variability of the late Holocene ichthyoarchaeological record in two environmental areas: the lower valley of the Chubut River, along with its mouth and adjacent marine coast. According to environmental productivity, high-ranked resources availability and capture opportunities, a subsistence model is generated. This model evaluates diversity and relative importance of fish for the two areas. Zooarchaeological expectations inferred are discussed on account of faunal samples taken from different archaeological sites, such as Barranca Norte and Los Cangrejales Sur (located at the river mouth and marine coast), Loma Grande 1 and Cinco Esquinas 1 (located on the valley, at 30 and 18 km distance from sea). Results show differences in fish taxonomic richness with perch dominant in the valley sites, whereas a high range of fish was found at the river mouth and marine coast sites. Although an important contribution of fish registered in both areas was recorded; in residential camps at the river mouth fish remains were scarce.