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Saprolegniosis |
Tail
rot/ Fin rot |
Ichthyophthiriosis |
Dactylogyrosis |
Argulosis |
Asphyxiation |
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Cotton-wool-disease |
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White
spot |
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Fish
lice |
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Causative
agent |
Saprolegnia
parasitica |
Flexibacter
columnaris/ Flavobacterium columnare |
Ichthyophthirius
multifiliis |
Dactylogyrus vastator |
Argulus spp (A.foliaceus, A coregoni, A japonicus ) |
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They
are normal water fungal inhabitants that invade the traumatized epidermis. |
They
are bacteria that cause putrefaction of caudal fin. |
They
are protozoan parasite that affects epithelia/sub-epidermis of skin, fins and
gills. |
They
are monogean trematodes whose free swimming
larvae(miracidia) attack the gills of the fish and feed on blood. |
It is a common crustacean ectoparasite
which lives on the fins and gills of the fish and sucks blood until full
adulthood is reached. |
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Appearance |
They
are branched, unsegmented, mycelium giving cotton-wool like appearance. |
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They
are uniformly ciliated, round, spherical or ovoid. Size-
upto 1mm in diameter |
It has 2 pairs of eyes at the anterior
end ,seven pairs of marginal hooks and on the haptor one pair of central
hooks with two prominences. Size mostly 0.2-0.5mm, never more than 2mm. |
It has broad, flat and oval body, head
and thorax (cephalothorax) is sunken
at the ventral side. •
Two complex faceted eyes: in the head and Sharp pointed dart or stylet
(sting/horn like) situated in front of the mouth between antennae. |
The minimum acceptable level of DO is 5 ppm. It is caused due to
low DO content of water. |
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They
are opportunistic facultative parasites that usually grow over previous
ulcers or lesions. |
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They
are cosmopolitian. Macronucleus is horseshoe (U-shaped)and micronucleus lies
to the concave side of macronucleus. |
They
are cosmopolitan and more likely to infect cultured water fish and marine
fishes. |
Attach to the fish by means of hooks and two suckers situated
under the eyes |
Frequently a problem during summer |
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Reproduce
asexually by means of biflagellate spores. |
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Three
phages in life cycle: Adult(infective), cyst and free-swimming. |
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Usually seen in fish ponds with a heavy algal
bloom. |
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Sign
and symptoms |
Fish
develop white to brown cotton like growths on skin, fins, gills and dead
eggs. |
A more or less distinct white line is seen at the
margin of the fin in early stages of the diseases. This line moves towards the base
of the fin and the fin becomes torn and after sometimes the entire fin is
completely destroyed. |
The disease is characterized by appearance of white
spots on the skin, gills, fins and cornea of the eye. |
Gill flukes cause loss of gills function
and behavioral characteristics indicating partial suffocation. |
The Argulus affected
fish shows red blotches
on the skin that are caused by the parasite. |
·
Suffocation, ·
Fishes come to water surface, ·
Gulp air bubbles very frequently ·
Congregate at water inlet ·
Mouth wide open ·
Opercula raised and gills spread
wide apart |
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In
early infections, skin lesions are grey or white in colour with a
characteristic circular or crescent shape which can develop rapidly causing
destruction of epidermis. |
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The fish react to the infestation of parasites by
irritation, flashing and rubbing on the bottom, swimming violently and
holding the fins close to the body. |
The fish become lethargic, swim near the surface, seek the sides
of the pond and refuse food . |
The fish show
nervousness and scratch themselves to get rid of the parasite. |
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Lethargy
of fish and loss of equillibrium. |
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More severe attacks result in skin detachments. |
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Scales
are lifted away from surface of body. |
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When the gills become infected, they appeared pale
in colour and swollen, respiration become difficult and the fish aggregate at
the water inlet and die. |
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Necrosis
of fins and respiratory manifestations appear on fish when infection is
associated with gills. |
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Management
and control |
Prevented
by good management practices ·
Good water quality and circulation ·
Avoidance of crowding to minimize injury (especially during
spawning) ·
Good nutrition ·
One Saprolegnia identified, sanitation should be
evaluated and corrected |
Dip treatment ·
CuSO4 at 500 ppm for 1 min bath treatment ·
In dilute solution of Acriflavine has also proved to be very
effective against fin rot |
Control: The
ponds should be drained and dried after an outbreak, then treated with
quicklime for killing cysts. The wild fish should be prevented from entry through water
inlets. |
The best control procedures are careful
management and balanced nutrition. |
Draining and drying ponds will destroy
all stages of these parasites. |
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Use of
aerators ·
Surface agitation ·
Increase inflow to aerate water ·
Thinning the population of fishes |
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Treatment Common
treatments include KMnO4 , Formalin and povidone iodine solutions.
Over treatment can further damage fish tissue, resulting in recurring
infections. Bath
treatment ·
NaOH
(10-25 g/lit for 10-20 min) ·
KMnO4
(1g in 100 lit of water for 30-90 min) ·
CuSO4
(5-10g in 100 lit water for 10-30 min) Malachite
green oxalate (zinc-free) treatment at at 0.1-0.2 ppm for 1 hour or by
continuous flow to yield a final concentration of 0.05-0.075 ppm for several
days. |
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Treatment ·
Formalin: Daily bath 200-250ppm; Pond treatment:
15ppm It has been reported that fishes in ponds are
treated with 15 to 25 ppm while aquarium fishes are treated with 25 ppm on alternate days until
the infection is cleared. ·
Acriflavin: Bath 10 ppm 10-20 minutes ·
Sodium chloride : 1.5 to 2.5% for 10 to 30 minutes/ 7 Days ·
Potassium permanganate: 2-5ppm for pond treatment. It
must be remembered that organic matter reduces its potency. |
Treatment Dip treatment ·
affected fish in 5% acetic acid for 1 minute ·
1 minute dip treatment in Malachite green Bath
treatment ·
Malachite green 1:5000 can be used for daily flush ·
Bath the diseased fish in 2.5% NaCl for 1 hr ·
Use 0.7% NaCl for indefinite treatment |
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Duroclean, 0.3g per kg fish feed and fed for 3 days
consecutively with one day off and then again for 2 days. ·
Dipterex @0.25 ppm ·
The fingerlings can be dipped into potassium permanganate (KMnO4)
solution for 1 hour at 20 ppm when it is between 15-20°C or at 10 ppm when 21- 30°C before stocking. |
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Treatment of
white spot disease is difficult because of the variability of the time of completion
of the life cycle. Since the life cycle is
not synchronized and no drug has been found which kill encysted form that’s
why treatment must be prolong
and repeated frequently. The free-swimming phase is the best time to treat with chemical |
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