Histological development of digestive tract in discus, Symphysodon spp. larvae
2010
The present study provides information on the histomorphological development of digestive system of discus, Symphyosodon spp., larvae during the first month of life. Discus larvae are altricial at hatching, with an undifferentiated digestive tract and a large yolksac, which is completely consumed within 7 days. The mouth opens 3 days after hatching (DAH) and the larvae starts feeding on AF Artemia at 4 DAH when offered. At 3 DAH the digestive tract is differentiated with distinct esophagus, stomach anlage, and mid- and hindguts. At 5 DAH, discus larvae is an active feeder, equipped with partly developed jaws and ossified gill arches and an inflated swim bladder. The liver and pancreas are present and supranuclear inclusion vacuoles (SIV) appear in the hindgut for the first time. Gastric glands in stomach were first observed 7 DAH and proliferated by 11-13 DAH. SIV were a common feature in the midgut and hindgut epithelium until 15-23 DAH. Therefore, exclusive use of artificial diets should be postponed until 2-3 weeks after hatching.
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