Epizootic Ulcerative Syndrome (EUS) In Freshwater Fishes Infected

Abstract

Abstract: Epizootic ulcerative syndrome (EUS) is seriously damaging large numbers of commercially important fish species since last two decades. The disease is reported as activate especially from November to February at low ranges of light, temperature and salinity. Red spots, lesions and deep hemorrhagic abrasions were reported commonly on body of host fish. Mucus and surface membranes were found contaminated by a number of fungal spores and hyphae of Aphanomyces and alternaria. Deep ulceration may cause the death of host fish.

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SINDH UNIVERSITY RESEARCH JOURNAL (SCIENCE SERIES)
Epizootic Ulcerative Syndrome (EUS) In Freshwater Fishes Infected By Fungal Genera Aphanomyces and
Alternaria, Sindh, Pakistan
G.M. WADAHAR, M. H. CHANDIO, M. A. MAHAR*
Directorate of Fisheries Sindh (Inland) Hyderabad, Sindh, Pakistan.
Received 13th March 2012 and Revised 4th August 2012
1. INTRODUCTION
Since last two decades, epizootic ulcerative
syndrome (EUS) is seriously damaging large numbers of
commercially important culturable fish species during the
cold seasons in a large number of public waters of Sindh,
Pakistan. This disease appears from end of autumn to
early spring and affecting large numbers of fishes in
ponds and stagnant water bodies. Epizootic ulcerative
syndrome (EUS) is considered to be an infection due to
fungal genus Aphanomyces and Alternaria characterized
histological by penetrating hyphae surrounded by
granulomatous inflammation. It is referred to be as
Mycotic Granulomatoses (MG) and Red Spot Disease
(RSD (Blazer et al., 1999). On average, less than 10
zoospores of this fungus is enough to kill a fish, and even
infection by just a single zoospore can result in ulcerous
lesions that can lead to mortality (Mohan and Shankar,
1995; Lilley et al., 1998; Thompson et al., 1999; Johnson
et al., 2004). Fishes infected with Aphanomyces that
develops ulcerous lesions which ultimately lead to
extensive tissue necrosis (Blazer et al., 1999). The Thatta
is one of rich districts in Sindh and famous by aquaculture
point of view, besides the Keenjhar and Haleji freshwater
lakes, the river Indus also flow across the district. About
3200 fish ponds, 1000 public waters i-e natural lakes,
canals and semi natural depressions are under practice for
fish cultivation. Thousands of metric tons of fish
production in Thatta district per annum is also being
harvested. Majority of fish farmers are practicing the
poly culture system of carps species belonging to
family Cyprinidae.
The present study expressed the prevalence of
fungal species that caused the ulcerate lesions in fishes
and become the cause of death. The objectives of this
study were to examine infectivity of fish and preventive
measures to save the fish from this chronic disease.
2. MATERIALS AND METHODS
The effected fish farms were surveyed during
November 2011 to February 2012. Water and effected
fish samples were collected from ponds of public waters
of district Thatta, preserved in sterilized plastic bottles
and poly-thin bags brought to the laboratories at
Department of Fresh Water Biology and Fisheries,
University of Sindh, Jamshoro and Fish Hatchery Chilya
Thatta. Physico-chemical parameters of water especially
temperature, pH and salinity (‰) were examined on spot
using the mercury thermo meter; pH meter model-98107
and salinity meter model M-98302. The microbiological
samples from ponds were collected with the help of nano-
plankton net (mesh size 55µm) especially for analysis of
fungal spores and preserved in 5% formalin solution.
Infected fishes (alive) were collected with the help of
hand nets transferred to antiseptic nursery size 25x50 ft.
The sample of mucus and tissues from lesion’s part of
affected fish were collected with fine sterilized blade
studied with the help of DCM 350 (0.1 USB) under the
trinocular microscope at x400 and x1000. Therapeutic
action was immediately started externally using mixture
of antibacterial chemical solutions (sprit 50%,
Benzebiotic 30% and Piodine 20%) and fatty ointments.
Each fish was treated once time in a day. Oxytetracycline
and Diclofenic sodium injections 0.4 cc dosage per kg of
body weight of fish were given/ day for a week.
3. RESULTS
The effected live fishes were collected and
placed under the first-aid. The mucus and surface
membranes from lesion’s parts of effected fish were
Abstract: Epizootic ulcerative syndrome (EUS) is seriously damaging large numbers of commercially important fish species since last
two decades. The disease is reported as activate especially from November to February at low ranges of light, temperature and salinity.
Red spots, lesions and deep hemorrhagic abrasions were reported commonly on body of host fish. Mucus and surface memberanes were
found contaminated by a number of fungal spores and hyphae of Aphanomyces and alternaria. Deep ulceration may cause the death of
host fish.
Keywords: Freshwater Fishes, Fungal Genera Aphanomyces and Alternaria,
Sindh Univ. Res. Jour. (Sci. Ser.) Vol.44 (4) 663-666 (2012)
++Corresponding Author G.M. WADAHAR cell. No. +92-3337174775
*Department of Fresh Water Biology and Fisheries, University of Sindh, Jamshoro, Sindh, Pakistan.

examined under the microscope and observed activeness
of fungal motile spores of Aphanomyces sp. (Fig.1). 50
liter volume of water samples were collected from
effected habitats strained through plankton net (no. 25,
mesh 55µ) that proved the presence of 5 to 7 number of
spores and hyphae of Aphanomyces and Alternaria. The
Aphanomyces motile spores were dark brown in color,
oval shaped 2-3 µm in diameter, while the shape of
Alternaria spores were rounded frontal and last part was
pea shaped and in hyphae the cells were arranged in a
graded series of diminishing size. Length measurement of
hyphae was 67-72 µm (Fig. 2-3). Five to ten numbers of
small and large sized fish were found in dead form in
ponds affected by epizootic ulcerative syndrome (EUS)
during cold weather at temperature ranges 11-17 ºC and
salinity 0.05 to 0.2ppt on daily basis. Mislaid of scales
and skin were also found at early stage, afterward small
lesions and red spots overall on the body were noted (Fig.
4). After 10 days gape the effected waters were again
surveyed and investigated the position of disease, thus
many ulcer spots were found on different parts of the
body even heads and in few specimens ulcers were seen
to extend down to abdominal cavity sides (Fig.5-8). Each
fish was treated once time in a day. Oxytetracycline and
Diclofenic sodium injections 0.4 cc dosage per kg of body
weight of fish were given/ day for a week. 60%
positive response was received by the application of
fatty ointments.
4. DISCUSSION
The syndrome has been reported broad-based
occurring in culturable species in Southeast Asia (Roberts
et al., 1993), Japan (Egusa and Masuda, 1971; Hatai
et al., 1977; Wada et al., 1996) and Australia (Fraser
et al., 1992; Lilley and Roberts, 1997). This most
destructive disease occurring both fresh and brackish
water farmed and wild fish which caused major fish
losses in many countries for over last three decades
(Baldock et al., 2005).
The similar epizootic ulcerative syndrome was
reported on the body of carps Catla catla, Cirrhinus
mrigala, Hypomichthyces molitrix, Hypophthalmichthys
nobilis and snake head Channa marulius in public waters
of Sindh, Pakistan, during cold seasons and low salinity
ranges. EUS disease in fishes was reported from waters
having low light, temperature and salinity. The spores of
Aphanomyces and Alternaria developed abundantly in
waters due to use of unhygienic organic dung and old feed
and fishes are affected severely. The Alternaria species
are commonly found in decay and decomposed materials.
The spores are air-born but commonly found in the soil
and water. The human health disorders can be caused by
Alternaria, which grow on skin and mucous membranes,
including on the eyeballs and within the respiratory tract
(Wikipedia encyclopedia). The same situations were
reported in the carp fishes by damaging the skin, gills and
eyeball. Infections happened by motile spores of fungus
in the water captivated and enter to the skin of fish and
then germinated, forming fungal filaments or hyphae. A
variety of saprophytic Aphanomyces, Achlya and
Saprolegnia species isolated from the surface of EUS-
affected fish or from infected waters, and Oomycete fungi
involved in other diseases of aquatic animals (Lilley,
1997). Disease was reported active form cold seasons in
low temperature during winter to early spring and
affecting large numbers of fishes in ponds and stagnant
public waters even reported in estuarine fishes like
mullets (Mckenzie and Hall, 1976). Epizootic condition in
freshwater fishes a complex infectious aetiology character
caused by the presence of invasive Aphanomyces
infection and necrotising ulcerative lesions typically
leading to a granulomatous response (Roberts et al.,
1993). The same situations were observed in effected
fishes found in Sindh.
Tilapia is considered as one of the resistant
species to EUS (Lilley et al., 1998). Pradhan et al (2008)
conducted experiments with Aphanomyces invadans in
advanced fingerlings of four different carp species for 12
days and found 100% mortality rate in major carps. In the
present investigation the mass mortality and infections
were recorded in carp and snake head species. Fatty
antibiotic ointments gave positive results from treatment
and cure point of view.
G.M. WADAHAR, et al., 664

Fig. 1. Aphanomyces zoospores collected from mucus lesion area of carp fish
Fig. 2. Alternaria spore Fig. 3. Alternaria hyphae
Fig.4. Red-spots on host fish Fig.5. Deep hemorrhage ulceration
Fig.6. Lesion on head region of fish. Fig.7. Ulcerative lesion near tail of fish.
Epizootic Ulcerative Syndrome (EUS) In Freshwater… 665

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