Finfish bacterial disease and their management

1. BACTERIAL DISEASE OF
FINFISH AND THEIR
MANAGEMENT
PRESENTED BY:- RUCHIKA SHARTMA
M.F.Sc. 1YEAR

2. Furunculosis Disease(Gram negative
bacterial infection)
 Causative Agent:- Aeromonas salmonicida(obligate
pathogen)
 Symptoms:- In old fish lethargy,
slight exophthalmia blood shot fins, bloody
discharge from the nares and vent, and multiple
haemorrhages in the muscle and other tissues.
Internally, haemorrhages in the liver, swelling of the
spleen, and kidney necrosis may occur.
 In growing fish and adults- darkening in
color, lack of appetite, lethargy and small
haemorrhages at the base of fins. Affected fish may
die within 2-3 days and causes high mortalities.

3.  Control measures:- Adequate husbandry practices
such as maintenance of good water quality, disinfection
of fish farm where outbreaks occurred and routine
disinfection for eggs. Stocking of fish farms with
disease-resistant strains of fish and the development of
effective vaccines also improve the health of fishes and
use of antimicrobial compounds.
 Treatment:-
 Chemotherapy used:- Sulphamerazine given orally
with feed at a dose of 22 g of drug / 100 kg of fish /
day.
 Chloramphenicol and oxytetracycline were dosed 5-7 g
/ 100 kg of fish / day. Vaccines have been used to
prevent the furunculosis successful.

4. Haemorrhagic septicaemia(Gram
negative bacterial infection)
 Causative Agent:- Aeromonas hydrophila
 Symptoms:-
 Small surface lesions, local haemorrhages
particularly in the gills and vent, ulcers,
abscess, exophthalmia and abdominal distension.
 Internally, there may be accumulation of ascitic
fluid , anemia and damage to the organs, notably
kidney and liver.

5.  Red sore disease:- caused by A. hydrophila,
characterized by erosion of the scales and pin-prick
haemorrhages which may cover up to 75% of the
body surface with a high mortality rate.
 Treatment:-
 Chemotherapy used- chloramphenicol and
nifurpirinol, oxytetracycline and sulpham-erazine
have been used.
 A polyvalent vaccine would be necessary for
combating this disease.

6. Pasteurellosis Disease
 Causative Agent:- Pasteurella piscicida
 Symptoms:-
 The affected fish show prominent white granules in
the kidneys and spleen.
 Pasteurellosis is one of the most important bacterial
disease among young cultured marine fish in Japan.

7.  Control measures:-
 Avoidance of over crowding and feed
management may prevent out-breaks of this
disease.
 Ampicillin, amoxicillin, novobiocin,
chloramphenicol florfenicol, oxolionic acid,
flumequin and sodium nifurstyrenate are used to
control bacterial pseudotuberculosis.

8. Edwardsiella septicaemia
 Causative Agent:- Edwardsiella tard
 Symptoms:-
 This disease occurs in the summer months with an
optimum temperature of 300 C.
 The diseased fish hang listlessly at the surface
with a head-up-tail down position, sometimes
spinning rapidly increased, usually followed by
death.
 Hemorrhage or inflammation occurs in the skin
under the jaw on the opercula and belly.
 The kidney and spleen are enlarged and spleen is
dark red.

9.  In chronically infected fish, an open lesion will
develop between the frontal bones of the skull,
posterior to or between the eyes.
 Affected fish have pale gills, exophthalmia and
often an enlarged abdomen. Internally, the body
cavity may be filled with a cloudy, bloody or rarely
a clear yellow fluid.
 Control measures:-
 The use of antibiotics incorporated into the feed.
Oxytetracycline and a potentiated sulfonamide are
the only drugs currently in use.
 Since the appetite of the fish in lost after some
time the medicated feed should be given early in
the epizootic.

10. Bacterial Gill Disease
 Causative Agent:- Yellow pigmented bacteria
(YPB) {cytophaga-like bacteria (CLB)}
 Symptoms:-
 Affected fish become lethargic and anorexic, they
tend to remain near the surface or inlet and may be
observed flaring their opercula and coughing their
respiratory rate is elevated and mucous secretion
may increase.
 Early stages include hyperemia, swelling of the
primary lamellae and increased mucus secretion
which traps debris.

11.  Control measures:-
 Environmental quality should be maintained by
avoiding over crowding, low dissolved oxygen,
suspended solids and high ammonia levels.
 Treatment:-
 Use of 1-5%, NaCl2 for 1-2 minutes.

12. Vibriosis Disease
 Causative Agent:- V. anguillarum
 Symptoms:-
 Occurs in warm weather, when the stocking
densities are high and salinities and organic loads
are also high.
 Signs of the disease are anorexia, with darkening of
whole fish or particular areas.
 Gills are pale and fibrinous adhesions occur
between visceral and parietal peritoneum.
 The eye may get infected and ulcerated.

13.  Severe necrosis of muscle with internal ulceration
occurs.
 In the liver, there is focal necrosis and in the
spleen and kidney, massive depletion and necrosis
of hematopoietic elements.
 Control measures:-
 Maintenance of water quality, good husbandry and
low stocking densities.
 Vaccines administration is by injection, oral and
immersion method.

14. Streptococcosis Disease
 Causative Agent:- Streptococcal septicemia
 Symptoms:-
 Erratic swimming, darkening of body color,
unilateral or bilateral exophthalmia, corneal
opacity, hemorrhages on the opercular and the
base of the fins
 Ulceration of body surface.

15.  Control measures:-
 Fluorescent antibody technique is the most rapid
and effective method for diagnosis of streptococcal
infection.
 Reducing over crowding, overfeeding,
unnecessary handling or transportation and the
prompt removal and slaughter of all moribund fish
in ponds or net cages at an early stage of infection
may prevent outbreaks or reduce their severity.
 Treatment:-
 Erythromycin given at does of 25-50 mg / kg body
cut of fish / day for 4-7 days.

16. Mycobacteriosis Diseases
 Causative Agent:- M. marinum, M.
fortuitum and M. Chelonae
 Symptoms:-
 Lightlessness, anorexia, emaciation, dyspnoea,
exophthalmia skin discoloration and external
lesions ranging from scale less to nodules, ulcers
and fin necrosis as signs of advancing infection.

18.  Control measures:-
 Natural spread of infection within a closed
environment may be controlled in the tank by the
adding of chloramine B or T at 10 mg/litre for 24
h after which the water should be changed.