1. In the Name of Allah,
the Most Beneficent, the Most Merciful.

2. Diagnosis of Aquaculture
Diseases

3. Disease means…………deviation
from normal condition either
behavioral, structure or physiological
state
You must know normal condition to
detect abnormal one……
………….easily to be done by
continuous observation

4. The aim of diagnosis process to
determine the accurate cause of the
disease the select the proper treatment
The owner should be advised to bring
both the fish (live and freshly dead )
and a water sample in separate clean
containers.

6. Steps of diagnosis
• Case history
• Clinical signs
• PM exam
• Lab exam (Parasitological, Bacterial,
Mycological, Virological and water quality)
• Histopathological exam
• Molecular methods to detect and
characterize the agent’s nucleic acid
• Biological test

7. I – Case History
1)Fish
2)Environment
A) Rearing unit
B) Water

8. 1)Fish
• Mortality

10. a) Recent rates Water problem O2 or toxic
b) Time
….early Has considerable morbidity
morning or
sudden
c) Species
Chronic or parasitic especially when affect some species
involved
d) Size and age
of dead fish

11. • All run facilities
b)Sudden change in routine
management
b) Usual routine for feeding as well
Change in diet quantity, quality or
forms. (fry, fingerlings or broad
stock). As well source and protein
percentages.

13. c) prior treatments, including
medications, have been given.
• Abnormal behaviour or function
of fish

14. 2) Environment
A) Rearing unit
• Type, size and location of the
facilities

15. 2. System of fish management
3. Stocking rate /stocking time

16. 4. Depth of water……….

17. 5. Presence of aquatic plants or
vegetations…O2

18. 6. Presence of natural enemies

19. 7. Habitat utilization …weeks ???
8. The surrounding of rearing unite
…human habituations, neighbor
infected farm

20. B) Water
1) Water source: sewages, underground water or surface water.

23. 2) Water exchange rates
3) Physical examination of water
- color and transparency… algae…
- turbidity
- smell…..amonia…..organic
matter

25. 4) Chemical examination of water
-Dis O2
- Ammonia, nitrite,
- pH………..acidic……Branchyomycosis
- Hardness……….soft water……Dee
disease
- heavy metals

26. II-Clinical sign
1- Behavioural Examination
General Exploration
• If a client submits live fish to
the clinic, aeration should be
immediately placed into the
container that holds the fish.
• (Examination of fish in water)

27. 1- swimming and movement

28. 2- escape reflex 3- sick fish easily caught
4- position of fish….TB

29. • flashing or itching (rubbing against objects
suggesting skin problems)
• piping (staying near the air - water interface to
obtain more oxygen, suggesting gill problems)
• Sick fish may exhibit other behavioral signs,
including staying near the surface of the water
= respiratory distress
• Extremely sick fish may be in dorsal or lateral
recumbency.

31. •scraping the body or holding the fins close to the
body ( “ clamped ” ) because of parasite irritation
•showing various behavioral abnormalities
•Sick fish often congregate together, separating
themselves from healthier
• Different fish species inhabit different parts of the
water column (surface, bottom, shoreline, etc.), and
this position often changes with sickness.

32. Clinical Examination
* Precautions during examinations
1. Fish should be carefully handled
2. Not allow fish to come in contact
with hard objects that affect slim
3. Examine fish on moist substances
4. Examine in shade and avoid wind to
prevent dryness
5. You examine by naked eye, stereo
microscope or magnifing lence.

33. 2- External examination:
- small fish can be examined at
moist palm, small plat

34. - large fish put on their right
side on moist glass or plastic
diaper. Put fish on their right
sides and held them by left
hands. Save eyes with palm of
hands and with other hands
support tail.

35. * Body inspection
1- color of the body
• Sick fish are often abnormally colored, compared
with the healthier
• Fish in breeding condition often have more brilliant colors than non
breeding fish
• Darkness over whole body…..chronic disease, bad water quality

36. - blacking of the tail and peduncle region…

37. Hemorrhagic lesions on body
surface or fins…..
Reddening of the body is usually caused by hemorhage, which can result
from systemic bacterial or viral infections

41. - white spots

42. - Grayish patches……

44. Fin rot

45. Parasites or other irritating conditions may also elicit a thickening of the
skin, leading to a whitish or bluish skin color. This change might be
highly localized (pinpoint to larger foci) or cover nearly the entire body

46. local tissue irritation/damage, such as parasite feeding,

47. chronic wounds, or healing wounds, which cause a change in the
pigment cell distribution at that site

48. 5- abnormalities in the vertebral column, mandible, nose…

50. Streptococcus
swollen vent, hemorrhage
8- abnormalities in anus, uorogenital opening or operculum

51. 2- Erosions or ulcers

53. 3- Exophthalmia of the eye……

56. 4- parasite can be seen by naked eye……..

58. 5- Distended abdomen or lost scales
Fluid filled body cavity- ascite

60. 6. Necrosis- dead tissue within a living
animal

61. 9- fecal examination
• Anesthesia often causes involuntary defecation,
allowing the collection of a fecal sample
• Fecal material can be obtained by siphoning debris
from the bottom of the tank

62. III.PM exam
Next sections in
details

63. Symptoms and signs of disease

64. Symptoms and signs of disease

65. Symptoms and signs of disease

66. Symptoms and signs of disease

67. Symptoms and signs of disease

68. Symptoms and signs of disease

69. 7. Swollen kidney, liver, inflamed
internal organs

70. SIGNS OF DISEASE
Brown gills
Pale gills
Eroded gills/excess mucus

71. Dasyrhynchus sp.
Cestode larvae in jack

72. IV. Histopathology

73. Gill Histology: Normal

74. Special histological / Cytological
techniques
1- Immunohistochemistry (IHC) /
Immunofluorescent chemistry (IFC)
Enables identification of agent or altered cell
receptor expression in relation to localization
within the body and within the tissue and in
relation to alterations in histomorphology.
Therefore, it facilitates the understanding of
potential pathogenicity.
3 - Electron microscopy

75. VI. Laboratory exam
(Parasitological, Bacterial, Mycological, Virological)
Start by killing of the fish by one of the
following methods
1- cut spinal cord
2- over dose of anesthesia
3- electric current
4- Catch the fish with dry towel and hit to hard
object
Not use chemicals in killing of fish especially in
bacteriological examination

76. VII. Molecular methods
1. Polymerase chain reaction (PCR)
The PCR reaction is ideal for detecting the
presence of bacterial, viral, parasitic
(protozoal or metazoal), or fungal
pathogens. The principle of detection is to
attempt PCR with primers that are
complementary to a part of the genome of
the pathogen, but not of the host.

77. 1.1. Conventional PCR protocols are for the
detection and identification of DNA
sequences
1.2. Real-time Taqman® PCR is a variation of
conventional PCR. This type of PCR can be
used to detect and quantify the load of an
infectious agent in clinical samples. It can
detect RNA or DNA sequences.
1.3. reverse transcriptase PCR (rtPCR)
protocols are for the detection and
identification of RNA sequences (RNA
viruses, bacteria).

78. General lines
1- DNA or RNA will be extracted from the samples
2- PCR reaction mix contains specific primers
3- replication in thermal cycler
4- The resulting PCR mix will be analyzed using
electrophoresis on a gel, to see if a band of the expected size

79. 2. Restriction fragment length
polymorphism (RFLP)/DNA
fingerprinting
• Used to identify a change in the
genetic sequence. Can be used to
trace inheritance patterns, identify
specific mutations, and identify
bacterial strains

80. 3. Microarray analysis
Used to detect gene expression. It
assesses the expression or activity
of a specific gene of an organism
by quantifying the amount of
mRNA the gene produces. not
commonly for the detection of
infectious agents.

81. 4. In-situ hybridization (ISH)
• Detects presence and location of
nucleic acids within lesions in order to
establish a link between infection and
disease.
• Based on identified labled nucleic
acid prob on histological sections
prepared by modified method.

82. • Stress may be a result of:
1) Poor water quality
2) Poor nutrition
3) ______________
4) Handling
5) ____________________
What causes fish to get sick?

83. • Fish are generally more vulnerable to
disease outbreaks during summer
months because:
1) _____________________
2) Dissolved oxygen
3) ______________________________
4) Disease organisms are more active at warm
temperatures
What causes fish to get sick?

84. Behavioral:
1) Slowing or Cessation of Feeding
2) __________________
3) Abnormal Distribution
4) __________________
5) Lethargic Swimming
Symptoms and signs of disease

85. Physical Symptoms and Signs
• I. Gross External Signs:
1) Production of Excess Mucus
2) _______________________
3) Eroded Fins, Gills, and/or Sores on the Body
4) _____________________________
5) Swelling or Cysts on the Body, Head, or Fins
6) _____________________________
7) Hemorrhages on Body Surface
Symptoms and signs of disease

86. Physical Symptoms and Signs
• II. Gross Internal Signs:
1) Discoloration
2) ______________________________
3) Lesions
4) Changes in texture of Organs, Tissues, and
Musculature
5) ________________________________
6) ________________________________
Symptoms and signs of disease

87. • Three major patterns:
1) Mortality due to ______________
___________________
3) Mortality due to ______________
___________________
5) Mortality due to ______________
__________________
Mortality Patterns

88. Mortality(# fish) Mortality(# fish)
A. B.
1 12 24
1 12 24 Time (days)
Time (hrs)
Mortality(# fish)
C.
1 12 24
Time (weeks)