Ontogenic development of the mouth and digestive tract in larval Malaysian mahseer, Tor tambroides Bleeker

Abstract

This study analysed morphology and histology of the developing mouth and digestive tract of the Malaysian mahseer larvae to assess the best weaning time to a compound diet for the fry on the basis of their morphological features. The mouth development was monitored using light and scanning electron microscopy; the development of the alimentary canal was followed histologically using light microscopy after haematoxylin-eosin staining. The larval mouth opened 1 day after hatching (1 DAH); the histological structures of oesophagus were completed by 5 DAH. At 2 DAH, differentiation of enterocytes began, and at 7 DAH the supranuclear protein inclusion appeared in the posterior intestine. The hepatopancreas was structurally completed at 4-5 DAH, coinciding with the start of exogenous feeding and the evidence of lipid storage in the liver. It was concluded that Malaysian mahseer larvae should certainly be able to ingest, and possibly digest and absorb, a formulated diet of 287 lm Ø from 7 DAH onward.

Histo-morphological development of the digestive tract of larval hybrid Malaysian mahseer (Barbonymus gonionotus♀ ×Tor tambroides ♂)

“…The presence of a short and straight digestive tract in newly hatched hybrid larvae was similar to findings of many earlier studies (Kamarudin et al, 2011;Ramezani-Fard et al, 2011;Teles et al, 2015) In this study, the number of goblet cells increased as the hybrid larva grew, whereby it started to disperse along anterior and posterior oesophagus by 5 DAH. Kozarić et al (2008) stated that goblet cells help to secrete mucus for the purpose of protecting the alimentary canal against physicochemical damage and bacterial attack.…”

Development of the digestive tract in first feeding larvae ofBetta splendensRegan, 1910

“…Taste buds appeared in the buccopharyngeal cavity at 32 hph. The presence of taste buds has also been reported on and in the oral cavity of Tor tambroides at 4 days post‐hatching (Ramezani‐Fard et al., ) and of Cichlasoma urophthalmus at 3 dph (Cuenca‐Soria et al., ). This tasting ability in the buccopharyngeal cavity enables the fish to decide whether to swallow or reject a food item that has been apprehended (Kasumyan, ).…”

“…Taste buds appeared in the buccopharyngeal cavity at 32 hph. The presence of taste buds has also been reported on and in the oral cavity of Tor tambroides at 4 days post-hatching (Ramezani-Fard et al, 2011) and…”

Effects of dietary fish oil replacement by various vegetable oils on growth performance, body composition and fatty acid profile of juvenile Malaysian mahseer, Tor tambroides

“…Similar to other mahseers in many countries, the natural stock of this species is rapidly declining in recent years (Ingram et al. 2007; Ramezani‐Fard et al. 2011).…”