Early development stages of the catfish Lophiosilurus alexandri Steindachner, 1877 (Pisces: Pseudopimelodidae) from the São Francisco River basin, Brazil

Lophiosilurus alexandri reproduces in captivity, has a high commercial value in Brazil and carries great potential for aquaculture. Research was carried out on L. alexandri larvae from days 1 to 30 post-hatch (DPH). Based on descriptions in the literature four developmental stages were observed using anatomic, histological and statistical techniques to provide useful data for the taxonomy, aquaculture and conservation of this species. In the yolk sac stage (1-2 DPH) the larvae presented myomeres (pre 17-23 and post anal 25-32) evident along the body, open mouth, the beginning of eye pigmentation and intestine with simple prismatic epithelium. The preflexion stage (3-4 DPH) was characterized by onset of body pigmentation and appearance of the pectoral fin bud. The oesophagus, stomach and intestine presented a folded mucosa. The flexion stage (5-7 DPH) was characterized by a flexion of the notochord, the chondrogenesis of the neural arches, formation of the dorsal and anal fins (11 rays) and appearance of the pelvic fin bud. In the postflexion stage (8-30 DPH) the formation of pelvic fin rays (6 rays) occurred along with the development of three different stomach regions. Except for the variables related to the yolk sac, all other studied variables presented significant differences between developmental stages.