This document summarizes the pathology of the digestive system in teleost fish. It describes diseases that can occur in the oral cavity, esophagus, stomach, intestines, liver, pancreas and swim bladder. Common diseases include lesions caused by hooks or pollution in the oral cavity, degenerative myopathy in the esophagus, bacterial and ascites lesions in the stomach, viral diseases like IPN and IHN in the intestines, hepatic necrosis, lipid infiltration and granulomas in the liver, and IPN, CCVD and IHN affecting the pancreas. Diagrams show the normal structure and examples of pathology for each organ.

1. Md.Atick Chowdhury

2. Systemic Pathology of Teleost
The Integumentary System
The Respiratory System
The Digestive System
The excretory System

3. The Digestive System
 Digestion is the process of converting food into
smaller compounds that can be used by the body.
 Mouth Buccal Cavity Phyrynx
Oesophagus Stomach Pyloric caeca
Intestine The Pancreas Liver Rectum
Anus

4. The Digestive System
Figure: Teleost Digestive System

5. Oral Cavity
 The oral cavity of the teleost is a hard, bony structure,
which is well adopted to prehension of rough
materials.
Common Diseases:
Lesions:
 Caused by fishing hook & developed into infected ulcers.
Necrotic fungal infection:
 Occur in upper jaw.
Neoplasia:
 Lesion of the lips or of pharynx.
 Caused by polluted water.

6. Oral Cavity
Figure: Normal Structure of Oral Cavity
Figure: Pathology of Oral Cavity

7. Oesophagus
Oeosophage is situated after pharynx, a muscular tube
that leads to the stomach.
Common Diseases:
Degenerative myopathy:
o Develop in muscle of oesophagus.
o Occurs due to vitamin E.
Figure: Normal Structure of Oesophagus Figure: Pathology of Oesophagus

8. Swim Bladder
 A gas-filled structure in many fishes that functions to
maintain buoyancy & helps in respiration.
 Common Diseases:
 Oedema:
 Caused by chronic bacterial infection.
 Inflammation:
 Due to raise of temperature.
 Distension:
 Assosiated with pathological lesions.
 Due to feeding on dusty food.

9. Swim Bladder
Figure: Normal Structure of Swim Bladder
Figure: Pathology of Swim Bladder (1: Inflammation, 2: Distention, 3: Oedema)
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10. The Stomach
After oesophagus true stomach is found.
Common diseases:
Bacterial lesions:
 Occurs occasionally within the muscular is of the stomach
and external serous.
Ascites:
 Increased fluid found in stomach cavity.

11. The Stomach
Figure: Normal Structure of Stomach
Figure: Pathology of Stomach

12. The Intestine
The intestine is a long thin tube with a thin double
layer musculature.
Common diseases:
IPN (Infectious Pancreatic Necrosis):
 Infectious Pancreatic Necrosis Virus
 Does not take food
 Fish show abnormal distension
IHN (Infectious Haematopoietic Necrosis):
 Infectious Hematopoietic Necrosis Virus (IHNV)
CCVD (Channel Catfish Viral Disease):
 Channel Catfish Virus (CCV)
 Abnormal movement
 Swelling

13. The Intestine
VHS (Viral Hemorrhage Septicemia):
 VHSV (Viral Hemorrhage Septicemia Virus)
 Dark color on intestine skin
 Swollen structure
Chronic infection:
 Caused by fungus such as Mycrobacterium or Nacardia
asteroides.
 Focal granullomatous infecton of the gut wall

14. The Intestine
Figure: Normal Structure of Intestine
Figure: Pathology of Intestine

15. Liver
 It has no specific shape and has 2 or 3 tissues.
 Common diseases:
 Hepatic Necrosis:
 Diphyllobothrium sp., Aeromonas salmonicida
 Nausea, weakness, abdominal pain.
 Lipid infiltration:
 Fatty infiltration of liver cell is common in farmed fishes.
 Liver enlarges
 Yellow or light brown color
 Loses its sharp edge of its lobes.
 Hepatic granuloma:
 Caused by a wide range of pathogen.
 Renibacterium salmoninarum, Mycobacterium fortuitum.

16. Liver
 Euclinostomum:
 Caused by Digenean parasites.
 Blood vessel degeneration:
 Blood vessel degenerates rapidly.
 Vaccume:
 Cell reduced causing vaccume condition.
 Bacterial colony:
 Several bacteria attacks & forms colony.

17. Liver
 Pigment accumulation:
 Most common is accumulation of ceroid and lipofuscin
 These byproduct catabolism are seen in liver cells &
hemopoietic tissue.
 The biliary system:
 It includes gallbladder, bile ducts and certain cells inside the
liver & bile duct outside the liver.
 Protozoan parasites are frequently observed in the gallbladder.
 Pathological changes resulting from biliary disease depend on
the level of the lesion.

18. Liver
Figure: Normal Structure of Liver
Figure: Pathology of Liver
Figure: Digenean sp.

19. Pancreas
Pathology of the teleost pancreas is complex.
Pancreatic tissue located in externa around the portal
vein system within the liver.
Common diseases:
 IPN (Infectious Pancreatic Necrosis):
 Infectious Pancreatic Necrosis Virus
 Responsible for acute & chronic exocrine pancreatitis.
 Affected fish have massive necrosis of the pancreas and
mortalities can be 20-30%
 CCVD (Channel Catfish Viral Disease):
 Channel Catfish Virus (CCV)
 IHN (Infectious Haematopoietic Necrosis):
 Infectious Haemopoietic Necrosis Virus

20. Pancreas
Figure: Normal Structure of Pacreas
Figure: Pathology of Pancreas

21. Thanks
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