The barred sand bass Paralabrax nebulifer, is a commercially important species in Baja California Sur, to date its digestive ontogeny in its initial phases of life has not been described. The objective of the present study is to describe the morphology of the digestive system of the verdillo at the beginning of the exogenous feeding until the transformation to the juvenile.
From verdillo reproducers, kept under controlled conditions of photoperiod and temperature, a static culture system was established in tanks of 250 l at a density of 33 embryos / l. The experiment lasted 32 days after hatching (DAH) with an average temperature = 23 ° C, and a mixed feeding scheme of live food (rotifers - Brachionus plicatilis and artemia - Artemia sp.) and three different aquaculture feed with varying particle size. From 5-20 organisms were selected daily and fixed in Davidson. Longitudinal and transverse sections 3 µm thick were made, which were stained with the histological techniques of hematoxylin and eosin (H&E) and periodic acid shift and alcian blue (PAS/AB).
The histological review made possible the identification of 4 phases of development. In the free embryo phase (0 - 3 DAH) we see an undifferentiated tube and hepatic tissue, being the oil globule the main source of nutrition in this early stage.
In the finfold larvae phase (3 – 16 DAH), the esophagus and intestine show a developed differentiation with the increase of surface area and epithelial folds, in contrast with the stomach which is less developed.
In the finformed larvae phase (16 – 25 DAH) the stomach presents a matured morphology, although there is no evidence of its functionality. The juvenile phase (25 DAH) consists of total maturity and functionality of the digestive tract as evidenced by the pyloric caeca.