Since the 1980s, brominated flame retardants (BFRs) have been detected in air, sewage sludge, sediment, fish, shellfish, birds, and mammals, including humans. However, model studies regarding BFR food-chain accumulation are scarce. In the present study, the accumulation of hexabromocyclododecane and brominated diphenyl ethers (BDEs) 47, 153, 154, and 183 in benthivorous barbel (Barbus graellsii) and pelagic bleak (Alburnus alburnus) from four locations in the Ebro river basin in Spain was modeled using a first-order, one-compartment model with sediment interaction. The model accounted for BFR uptake from water, ingested sediment, and food; release via water and feces; growth; and in situ binding of BFRs to black carbon. Rate constants were derived from allometric regressions. For most BFRs, dynamically modeled biota-sediment accumulation factors (BSAFs) were close to measured values, whereas steady-state model BSAFs were too high, especially for BDEs 153, 154, and 183. Differences between BSAFs for individual fish were explained by differences in age, growth, and feeding behavior. On average, modeled BSAFs for barbel were 50% higher than those for bleak because of extra BFR uptake through sediment ingestion and older age of barbel specimens.