The widespread increase of pesticides application in crops frequently leads to the contamination of vicinal freshwater lentic ecosystems. Herbicides such as propanil may impair cladoceran fitness, which is per se strongly influenced by the food availability and/or its acquisition efficiency. This work intended to evaluate the responses of Daphnia magna and three clonal lineages belonging to the Daphnia longispina complex to acute and chronic exposures of the herbicide propanil, as well as to assess whether food availability features these responses. Results showed that the agrochemical was acutely and chronically toxic to both D. magna and the D. cf. longispina clones at the same range of low concentrations, while relevant differences were depicted between the three distinct genotypes belonging to the D. longispina complex. Food-level conditioned the general fitness of the daphnids in the tests but evidences suggest that it does not interfere specifically with the toxicant mode of action.