Digestive System of Fish


Acquisition of nutrients and energy essential for metabolism and growth in fish involves the processes of secretion, digestion and absorption and, in some cases, unique structures such as pyloric caeca or a spiral valve. The digestive tract is also involved in electrolyte and water balance.

Keywords: digestion; absorption; secretion; electrolytes; hormones

Figure 1.

Digestive tracts of four species to illustrate partially the range of gut morphology in bony fishes. (a) Common carp (Cyprinus carpio); (b) rainbow trout (Oncorhynchus mykiss); (c) zebraperch (Hermosilla azurea); and (d) paddlefish (Polyodon spathula). CS, cardiac stomach; HBC, hindgut blind caecum; HC, hindgut chamber; I, intestine; O, oesophagus; PC, pyloric caeca; PS, pyloric stomach; R, rectum; SV, spiral valve.

Figure 2.

Absorption of the final products of protein, carbohydrate and lipid digestion in the enterocytes of the intestine. Red circles, Na+‐dependent active transporters; green circles, Na+‐independent active transporters; blue circles, facilitated diffusion; yellow‐tipped arrows, passive diffusion; black circles, chylomicron.


Further Reading

Buddington RK, Krogdahl A and Bakke‐McKellep AM (1997) The intestines of carnivorous fish: structure and functions and the relations to diet. Acta Physiologica Scandinavica 161 (supplement 638): 67–80.

Clements KD (1997) Fermentation and gastrointestinal microorganisms in fishes. In: Mackie RI and White BA (eds) Gastrointestinal Microbiology, vol. 1: Gastrointestinal Ecosystems and Fermentations, pp. 156–198. New York: Chapman & Hall.

Collie NL and Ferraris RP (1995) Nutrient fluxes and regulation in fish intestine. In: Hochachka PW and Mommsen TP (eds) Biochemistry and Molecular Biology of Fishes, vol. 4: Metabolic Biochemistry, pp. 221–239. Amsterdam: Elsevier.

Horn MH (1998) Feeding and digestion. In: Evans DH (ed.) The Physiology of Fishes, 2nd edn, pp. 43–63. Boca Raton: CRC Press.

Jobling M (1995) Environmental Biology of Fishes. New York: Chapman & Hall.

Loretz CA (1995) Electrophysiology of ion transport in teleost intestinal cells. In: Wood CM and Shuttleworth TJ (eds) Fish Physiology, vol. 14: Cellular and Molecular Approaches to Fish Ionic Regulation, pp. 25–56. San Diego: Academic Press.

Stevens CE and Hume ID (1995) Comparative Physiology of the Vertebrate Digestive System, 2nd edn. Cambridge: Cambridge University Press.

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Horn, Michael H, and Gawlicka, Anna(Apr 2001) Digestive System of Fish. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0001838]