Morpho-histological characterisation of the alimentary canal of an important food fish, Asian seabass (Lates calcarifer).

Kathiresan Purushothaman,Shubha Vij,László Orbán,Syed Musthaq Sk,Declan Patrick Lunny,Doreen Lau,Jolly M Saju

doi:10.7717/peerj.2377

Abstract

Asian seabass (Lates calcarifer) is a food fish of increasing aquaculture importance. In order to improve our understanding on the digestive system and feeding of this species, morphological and histological features of the gut were studied. Morphologically, the Asian seabass gut is defined by a short and muscular esophagus, well-developed stomach and comparatively short intestine. Mucous secreting goblet cells reactive to PAS (Periodic Acid Schiff) and AB (Alcian Blue) stain were present throughout the esophagus. The stomach was sac-like and could be distinguished into the cardiac, fundic and pyloric regions. Gastric glands and mucus cells were predominately present in the cardiac and fundic regions. Five finger-like pyloric caeca were present between the stomach and intestine. The intestine was a short, tubular structure with no morphological differences between the various regions. Histologically, the intestinal regions were similar, the main difference being in the number of goblet cells that increased from anterior to posterior intestine, with 114 ± 9, 153 ± 7 and 317 ± 21 goblet cells in the anterior, mid and posterior regions, respectively. The intestinal epithelium stained positively for PAS, but the staining was stronger for acidic glycoproteins. The rectum was similar to intestine, except for increased goblet cell numbers (anterior rectum: 529 ± 26; posterior rectum: 745 ± 29). Gut morpho-histology did not respond to salinity changes, however, there was a significant reduction of mucosal height, goblet cell numbers and muscularis thickness upon food deprivation.

Highlights

The Asian seabass (Lates calcarifer; Centropomidae), known as barramundi or giant perch, is an important food fish in many parts of the world (Nelson, 2006; Vij et al, 2016; Vij et al, 2014)
Knowledge on the functional morphology of the alimentary canal would be useful for establishing a feeding regime for Asian seabass, a fish of increasing aquaculture importance, especially in South-East Asia
The Asian seabass is a carnivorous species, this feeding behaviour is reflected in its large mouth, oblique and wide upper jaw which enables the fish to swallow its prey as a whole (Pusey, Kennard & Arthington, 2004)

Summary

INTRODUCTION

The Asian seabass (Lates calcarifer; Centropomidae), known as barramundi or giant perch, is an important food fish in many parts of the world (Nelson, 2006; Vij et al, 2016; Vij et al, 2014). There has been an increasing interest in its growth mechanism and nutritional needs in recent years, especially with a view to improve the production of good fillet of marketable quantity and quality (Alhazzaa et al, 2011; Glencross et al, 2008; How to cite this article Purushothaman et al (2016), Morpho-histological characterisation of the alimentary canal of an important food fish, Asian seabass (Lates calcarifer). The fishes are generally fed with frozen bait fish and pelleted feed composed of both plant and animal contents (Glencross, Wade & Morton, 2013).They exhibit moderate cannibalism, and may prey on their smaller siblings (Davis, 1985).The alimentary canal is one of the major organ systems of fishes that interacts with the environment It plays a critical role in growth, nutrition, as well as survival of the fish under different conditions. This, in turn will help the development of an informed aquaculture program and further improve the management of Asian seabass stocks

Ethics statement

RESULTS

DISCUSSION