In bay snook (Petenia splendida) larvae the histological development of the digestive system and swim bladder, and their relative timing of differentiation were studied from hatching to 45 days post-hatch (dph) at 29°C. Newly hatched larvae showed a simple digestive tract, which appeared as a straight undifferentiated tube lined by a single layer of columnar epithelial cells (future enterocytes). The anatomical and histological differentiation of the digestive tract and accessory glands was a very intense, asynchronous process, proceeding from the distal to the anterior part. The intestine was the first region to differentiate (9 days post-hatch – dph, 6.5 mm SL), and the oesophagus the last (21 dph, 8.4 mm SL). At the onset of feeding, the digestive system was organized into different functional and histologically differentiated sections, such as the buccopharynx, oesophagus, glandular stomach, and anterior and posterior intestine. This organization resembled that of the juveniles, with the exception of pharyngeal teeth and buccopharyngeal as well as oesophageal goblet cells, which proliferated later during the mixed feeding period. Histological observations revealed that bay snook larvae retained endogenous yolk reserves until 24 dph (8.9 ± 0.4 mm SL), which might be helpful for weaning this species onto a compound diet. The important lipidic accumulation observed in the intestinal mucosa, liver, and pancreas in fish fed a compound trout diet indicated that although fish were able to digest and absorb lipids, the diet formulation did not fit the nutritional requirements of early juveniles of this species. The ontogeny of the digestive system followed the same general pattern as in most cichlid species described to date. However, we detected species-specific differences in the timing of differentiation that were related to their reproductive guild. According to the histological results, some recommendations regarding the intensive culture of this species are also provided.