he common shellfish diseases are listed and the known specific etiologic agents are indicated. The latter include viral, bacterial, fungal, protozoan, and metazoan parasitic and infectious agents. In addition, predators, toxic agents, and fouling organisms produce seri- ous economic losses.

1. Ashish sahu

2. TOPIC-SHELL FISH DISEASE
INDEX-
 DEFINITION of disease
 INTRODUCTION
 TYPE OF DISEASE
 DISEASE CAUSING FACTOR
 PRAWN DISEASE
 LOBSTER DISEASE
 CRAB DISEASE

3. DEFINITION OF DISEASE –
 “Disordered or abnormal condition of an organ or other
part of an organism resulting from the effect of genetic or
development error , infection , nutrition deficiency ,toxicity
,unfavourable environmental factor , illness, sickness”.
 “Any impairment of normal physiological function
effecting or part of an organism especially a specific
pathological change caused by infection ,stress etc.
Producing characteristics symptom ,illness or sickness”.

4. Introduction -
 Fish diseases usually do not have single cause ,they are
outcome of the many interaction such as-
1. HOST(FISH)
2.CAUSING AGENT(PATHOGEN)
3.ENVIRONMENT(STRESS)
 The incidence of fish diseases is an indicator of imbalance
relationship between host ,pathogen and environment.
 Formula of relationship-
H+P+S2=D
Where-H=HOST, P=PATHOGEN,
S=STRESS

5.  Aquaculture disease may caused several losses on fish
farm, shrimp farm by reducing growth and production ,
increase vulnerability to predatory increase susceptibility
to low water quality and lastly death of fish .

6. Types of disease -
Their are two type of disease-
1. Non communicable disease
2. Communicable disease
1. Non communicable disease – Are less importance and are
generally caused by nutritional deficiency and extremely
adverse environmental factors .
2. Communicable disease – More common occurrence and
some assume epizootic properties causing devastating
effect leading to some serious problem or economic loss.
Communicable disease are cause by Virus, Bacteria, Fungi
,several group of protozoan and Metazoan parasites.
.

7. Disease causing factors-
 Stress ,susceptibility of the host, pathogen , nutrition, &
water quality are some of the other factor which affect
fishes .
 Imbalance in vitamin content of fish diet are not the
only cause of nutritional diseases other form of
nutritional imbalance i.e. improper feeding can causes
liver degeneration ,anaemia .

8. A- Stress –
 A series of morphological , biochemical & physiological
changes produced by an environment or other factor .
 Cause of stress-
1 .Extreme or toxic condition of water bodies.
2. Rough and excessive handling.
3 .Harvesting or sortinggrading.
4 .Unsuitable water temperature .
5 .Lack of dissolving oxygen .
6 .Change in the pH towards extreme values.
7 .Presence of toxic gases such as NH4.
8. Higher stocking density.

9. B-Susceptibility of the host –
 Skin ,scales exoskeletons or shell and mucous membrane
, which physical barriers will limit the entry of the toxic
infection and parasite agent .

10. C- Pathogen –
 Those agent which cause disease to its host by
infectious particles which capable of producing
disease.
 Pathogen penetrate on the host to multiply and
invade the vital organ of the its host.
 Wounds in the skin are the common entrance
point for some of the Bacterial, Viral infection.

11. D- Nutrition –
 The science which deals with food and nourishment.
 The aquatic animal which not fed up properly , it
causes slowly but gradually nutritional disease.
 Various cause of the nutritional diseases –
1. Inadequate nutrition
2. Starvation –Increases’ cannibalism is often the first
sign of the problem .
3. Change in diet.
E- Water quality ---The water quality plays a
crucial role in disrupting the balance between host
and pathogen.

12.  Water quality parameter-
 Dissolved oxygen -5ppm
 pH range - 6.7-8.6
 Free total co2- 3mgl or less
 Alkalinity— 50 -100ppm
 NH3-0.02ppm or less

13. Prawn viral disease –
1 Monodon Bacculovirus disease-
Causative agent –Monodon baculovirus
Species affected – Penaeus monodon
Stage affected –Post larvae ,neo adults
Symptom –
 Lethargic and come to surface or sides.
 Affected shrimp exhibit pale bluish gray to dark blue
black colouration .
 Fouling organism infest the shrimp .
 There is a necrosis of the hepatopancreatic tubules
leading to disfunctions of the organ..
 Yellowish white hepatopancrease.
Note – The infection has been reported in coastal India
1994.

14. 2 Infectious hypodermal &
hematopoietic necrosis(IHHNV)
DISEASE-
Causative agent –Picorona virus
Species affected- P .monodon
Stage affected- Post larvae juvenile adult
Symptom-
 Erratic swimming behaviour.
 Rising slowly to water surface.
 The motion of pleopods and pereopods ceases and animal
sink in bottom.
 They die usually within 4-12.

15. 3.Hepatopancreatic parvo –like virus
(HPV)-
Causative agent-Parvovirus
Species affected- P .monodon , P. merguinsis
Stage affected- Juvenile and adult
Symptom-
 Retarded growth.
 Loss of appetite.
 Benthic diatom Protozoan such as Zoothamnium and
filamentous bacterial cause fouling on the exoskeleton.
 Occassional white opaque areas on the abdominal
muscles.

16. 4- White spot syndrome disease(WSSV)-
Causative agent- Unclassified virus (SEMBV, PJRV) ,belonging
to family –Nimaviridae.
Species affected- P .monodon , Lobster, Crabs, branchiopods,
Stomatopods, copepods etc.
Stage affected- Juvenile and Adult.
Symptom-
 Lethargic.
 Stop feeding with empty gut and develops gradually white spot
of variable size on the carapace .
 Seen surface the water non specific signs of ill health , including
damaged appendage and external fouling .
 Virus spreads both horizontally and vertically.
 White first appear on the carapace then at the last abdominal
segment , later spreading to the circular surface all over the
body .
 Mortality – within 5-10 days 100% mortality
Note – First report of WSD in 1994 in Andhra Pradesh.

18. 5-Loose shell syndrome- –
Causative agent- Unclassified virus
Species affected- P. monodon
Symptom-
 Loose exoskeleton and spongy muscle
 Poor feeding and growth rate
6-Prawn noda virus – Known as white muscle diseases
or white tail disease-
Causative agent M. rosenbergii noda virus (MRNV)
Species affected- Macrobrachium rosenbergii
Stage affected -Post larvae and Juvenile .
Symptom-
 Whitening of abdominal muscle giving rises appearance of
white tail .
 Lethargic and poor feeding.
 Mortality -30to 90%

19. Bacterial diseases –
1- Vibriosis –
Causative agent -Vibrio spp.
Species affected- All spp.
Symptom -
 Loss on appetite .
 Erectic swimming .
 Seen surface of water .
 Note only affected stressed shrimp.

20. 2.Shell disease or Necrosis
appendage –
Causative agent- Vibrio , Pseudomonas , Aeromonas .
Species affected- P. monondon , P. merguiensis , P. indicus
Stage affected- Larvae post larvae juvenile adult.
Symptom-
 Appearance of brownish to black erosion of the carapace
, abdominal segments , rostrum , tail, gill and
appendage.

21. 2.Filamentous bacterial disease–
Causative agent- Leucothrix spp.
Species affected- P .monodon ,P.merguiensis ,P. indicus .
Stage affected- Larvae , post larvae , juvenile and adult
Symptom-
 Presence of tiny colour less , thread like growth on the
body surface and gill as seen under a microscope .

22. 3.Black spot disease –
Causative agent- Vibrio spp.
Species affected- P . monodon , M. rosenbergii
Symptom-
 Black lesion are visible in muscle , abdomen , gill, and
other organ
 Development of black areas due to deposition of black
pigment

23. 4.Luminous bacterial disease-
Causative agent -Vibrio harveyi , V. Splendius
Species affected- P. monodon , P. indicus , P. merguiensis
Stage affected- Egg, larvae ,post larvae
Symptom-
 Larva become week and opaque white
 Continuous greenish luminescence when observed in total
darkness
 Affected 100% population.

24. 5-Septic hepatopancreatic necrosis
Causative agent- Vibrio spp.
Species affected- P . monodon
Symptom-
 Hepatopancreas turn black and are degenerated.
6-One mouth mortality syndrome
Causative agent -Vibrio spp.
Species affected- P . mondon
Symptom-
 Sudden mortality of young due decomposition material
formed on the pond by death of benthic algae
 Young ones after mortality come in contact with these
decomposing material on which profuse number of Vibrio
spp.

25. Fungal diseases -
1-Larval mycosis –
Causative agent- lagendium callinectes , haliphthoras
Species affected- P.monodon
Stage affected -Egg , larvae early post larvae
 Symptom-
 Infected egg, larvae and post larvae appear whitish ,
become week and eventually die

26. 2-Lagendium infection
Causative agent- Lagendium spp.
Species affected- P . monodon
Stage affected- Larvae
Symptom-
 An extensive mycelia network can be seen through the
exoskeleton can decimate hatchery population within 24 hrs
3-Infection by fusarium and
saprolegnia-
Causative agent- Saprolegnia spp.
Species affected- P . monondon
Stage affected- Larvae
Symptom-
 Cause necrosis and melanisation , follow physical damage .

27. Yeast infection –
Symptom
 Muscle appears yellowish bluish or grey.
Protozoan diseases –
1.Protozoan infection –
Causative agent- Vorticella acineta
Species affected- P . monodon ,P. merguiensis, P. indicus
Stage affected-Egg ,larvae ,post larvae and adult
Symptom-
 Attached to any external part of the shrimp
 Locomotion and respiration difficult y.

28. 2-Microsporidiosis or white ovaries
Causative agent- Microsporidiosis spp.
Stage affected- Juvenile and adult
Symptom-
 Affected tissue
 Infection may result sterility in adult with white ovaries
3-Gregarine disease –
Causative agent- Gregarines spp.
Species affected- P.monodon
Stage affected- Larvae ,post larvae juvenile and adult
 Symptom-
 Affected digestive tract

29. 4-Fouling disease
Causative agent- Epistyles, zoothamnium, vorticella, acinetta etc.
Stage affected- All prawn
Symptom-
 Affected gill ,body surface and appendages disrupting motility
Environmental and Nutritional
disease-
1-Black gill disease –
Cause
Symptom-
 Gill exhibit reddish , brownish or black discolouration and atropy .
 Loss of appetite
 Physical deformities
 Secondary infection by bacteria , fungi attack on the dying shell

30. 2-Red disease-
Cause –Presence of Aflatoxin in feed .
Symptom-
 High input of lime in pond.
 Sudden drop in feed consumption .
 Yellowish and eventually reddish discolouration of the
body and appendages.
 Red short streak on gill

31. Lobster diseases-
Bacterial disease-
 Red tail or Gaffkemia –
 Moebiasis
 Protozoan disease –
 Bumper car disease- or ciliate disease
 Shell disease –
Crab diseases-
Parasite diseases
 Parasite disease
 Bitter crab disease (blood disease)
Bacterial diseases
 Shell disease
 Grey crab disease

32. Molluscun diseases –
Viral diseases
 Akyo oyster disease-
 Withering syndrome –
 Molluscan contagiosum or water warts
Bacterial diseases –
 Nocardiosis
 Hinge ligament erosion –
 Bacterial abscess disease (BAD)
 Brown ring disease

33. PREVENTION AND TREATMENT
Disease Prevention and treatment
Monodon baculovirus Improve pond environment, low density
culture, no treatment reported
White spot Use SPF seed, good management, no
treatment reported
Loose shell syndrome Good management ,no treatment
reported
Noda virus diseases Obtain and maintain diseases free stock ,
good management use of diagnostic kit
Yellow head diseases Maintain water quality improve pond
bottom

34. Hepatopancreatic parvo like
virus
Obtain and maintain diseases free stock .
no treatment reported
IHHNV Obtain and maintain diseases free stock .
no treatment report
Vibriosis Improve water quality , diseases free
stock .
One mouth mortality
syndrome
Maintain algae in the pond , improve
environment of pond
Black spot Good management ,maintain water
quality . treatment in immersion of
10ppm oxolenic acid for 1 hr or2ppm
Nifupriniol for 96 hr reported .
Bacterial septic
Hepatopancreatic necrosis
Maintain water quality ,good
management .No treatment reported