Abstract
The initial ontogeny of black prochilodus (Prochilodus nigricans Spix & Agassiz 1829) was described through morphological, meristic and morphometric characters. The biological material used was from captivity. 41 eggs, 151 larvae and 10 juveniles were analysed. The eggs were spherical, transparent, nonadhesive and pelagic, with a wide perivitelline space and an average diameter of 2.62 mm. Hatching occurs between 17 and 18 h after fertilization. The standard length of larvae varied from 3.28 to 26.73 mm and that of juveniles from 28.99 to 42.90 mm. The larvae showed an elongated and fusiform body, a convex dorsal profile, a long intestine, extending beyond the median region of the body, a terminal mouth and fleshy lips. The complete sequence of fin rays formation was caudal, dorsal (I,11), anal (I,11), pelvic (9) and pectoral (I,16–17). The number of myomeres ranged from 44 to 46, with mode 45 (n = 122). Growth analyses indicated early and late developmental metamorphosis. P. nigricans presents embryonic and larval development characteristic of fish with telolecithal eggs, in which the newly hatched larva does not yet have all the organic systems fully formed, is limited to a few organs and is still dependent on the yolk for its nutrition.
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