SUMMARY: For successful fish larviculture thorough studies describing the development of fish in different morphological aspects are required, as they are crucial for larval survival and growth. The present study described in Prochilodus lineatus larvae the osteological development of the vertebral column and caudal skeleton 30 days after hatching (dah). Larvae were obtained by artificial induction of adults. The beginning of formation of the spine occurs between 10 to 12 dah (8.3 mm standard length, SL) simultaneously to the first neural and hemal processes and the pre-caudal vertebral bodies. The ossification of the vertebral column occurred in cranio- caudal direction and was completed at 28 dah (22.6 mm SL). The development of the caudal skeleton elements started between 6 and 8 dah with the formation of the hypurals (H), the parahipural (PH) and the primary and secondary caudal rays. H 1 to H 3 were formed as cartilaginous primordia on the ventral side of the distal portion of the notochord, while the PH and H 4 to H 6 were formed subsequently. The first rays of the caudal fin were observed in correspondence with the formation of H 2 and H 3, while complete formation of the caudal fin was observed at 28 dah. The epurals, three in number, were evident as cartilaginous elements located both dorsal and distal in the notochord. Central ural complex (CUC) was formed by the fusion of three structures, the center preural 1 and urals 1 and 2. Development of the vertebral column and the caudal skeleton in P. lineatus larvae showed similar patterns to those described for other teleosts.
KEY WORDS: Prochilodus lineatus; Larviculture; Osteological development.