Histopathological observations during larval rearing of common dentex Dentex dentex L. (Sparidae)

Histological observations in cultured common dentex Dentex dentex larvae are described from days 1 to 36 after hatching. No alterations were found throughout the lecitotrophic period. Following subsequent experimental starvation, larvae showed atrophy of the digestive structures, pancreatic degeneration and lack of supranuclear vacuoles in the hindgut. During transition from endogenous to exogenous feeding, 30% of 7- and 8-day-old larvae and 11% of 9-day-old larvae exhibited histological alterations similar to those described in starved individuals, regardless of the level of rotifer enrichment. During the Artemia feeding period, intestinal steatosis was a common feature, mainly from day 30 onwards. Swimbladder non-inflation rates ranged from 12% to 77%. By day 17, the batch of larvae showing the highest percentage of non-inflation exhibited the lowest growth performance. Histopathological alterations associated with bacterial agents were described only occasionally. No parasites were found in any of the specimens examined. It is suggested that nutritional factors, rather than infectious agents, are responsible for the high mortality encountered in cultured dentex larvae. © 2001 Elsevier Science B.V.