fish parasitological studies of thakurgaon, bangladesh and their impact on fish culture

Fish Parasitological Studies of Thakurgaon, Bangladesh and Their Impact on Fish Culture

Md. Atick Chowdhury B.Sc. Fisheries (Hons.), Level: 02, Semester: 02, Faculty of Fisheries

Sylhet Agricultural University, Sylhet-3100

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Introduction: Bangladesh is one of the world’s leading fish producing countries and it’s total

fish production shows a consistently increasing trend from the fiscal year

1983-1984 to 2011-2012 and the production increased more than four times

(754,000 MT in 1983-1984 to 3,262,000 MT in 2011-12). Indian major carps like

Catla catla, Labeo rohita, and Cirrhinus mrigala are considered as the major

cultivable fish species in inland aquaculture of Bangladesh and it contributes

around 85.29% of total pond fish production of Bangladesh. Along with

carps all the freshwater species found more or less to suffer with different

types of diseases while 15%-20% are associated with parasite infestation.

Indian major carps are highly susceptible to disease in comparison to Chinese

and European carps. The intensity of fish parasitic infection is greatly

influenced by seasonality, which affects host ecology as well as physiology.

Intense parasite infection can cause ulceration and upset the normal course of

reproduction. Parasites interfere with host nutrition, metabolism and secretary

functions of the alimentary canal and can even damage the host nervous

system. All these effects may reduce normal growth of the fish and finally

induce the host mortality.

Parasite: The term of parasite is originated from two Greek words ‘para’ means ‘beside’

and ‘sitos’ means ‘food’. So, parasites are those animals which cling to

relatively large animals of different species externally or internally for food and

also for completion of their life cycle. The parasites are metabolically

dependent on host.

Example: Lice

Fish Parasite:

The parasites which cling to fish body externally or internally for food and also

for completion of their life cycle is called fish parasite.

Example: Tape worm

Methodology: Fish parasites are available all across the country. The type of parasite in or

clinging to a host fish may be different according to season and place. So, the

investigation of fish parasites according to area basis can be a great document

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for parasitological study. This investigation can ease our work to gather

information about the fish parasites available in our country, their effect,

occurance period, problem regarding to production, preventive measures etc.

Description: My hometown is Thakurgaon under Rangpur division. So, my task was to figure

out fish parasites available in my locality and their impact on fish culture

system. So, during Eid vacation, I went to the nearest District Fisheries Farm

and discussed with the present District Fisheries Officer (DFO), Md. Abdus

Sattar there about the topic. Later, I also discussed my assignment topic and its

subject matter with Md. Latifur Rahman, District Fisheries Officer, Lalmonirhat

who is the previous DFO of Thakurgaon. I have tried to find out all important

and adequate information about my given task and I think, I am quite

successful in this matter.

Parasites Available in My Locality: Through my investigation, I have figured out fish parasites like Argulus sp.¹,

Lernaea sp.², leech ², Ichthyophthirius multifiliis mainly and sometime round

worm² are also available in my locality.

The description with necessary information about available fish

parasites in my locality are given below.

1. Argulus sp. Classification: Kingdom: Animalia

Phylum: Arthropoda

Class: Copepoda

Order: Argulidea

Family: Argulidae

Genus: Argulus

Species: Argulus sp.

Common Name : Japanese fish louce

Parasite Type : Ectoparasitic

Figure: Argulus sp.

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Morphology: i. Light brown in colour

ii. 4 mm to 9 mm long and 3 mm to 6 mm wide iii. It has a stumpy tail iv. Flattened creature, spherical shape v. Two pairs of antennae present

vi. Two suckers for attaching to the skin of the hosts vii. Large hollow preoal sting or proboscis present to penetrating and feeds

on blood of its hosts

Distribution:

Mostly the carp species are affected by Argulus

Catla catla is very much affected

Occurs also in aquaria

Symptoms:

Can be seen with naked eye

Frequent rubbing or flashing

Localised redness

Production Problem:

Severely damage host, integument affected

Loss of appetite, sometime resulting death

Affect growth rate

Figure: Argulus sp. on fish skin Figure: Argulus sp. on fish fin

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Treatment: Pyrethum is a good therapeutic substance, dose is 20-100 ppm for 50

minutes

Bytex

Potassium permanganate (KMnO4)

2. Lernaea sp. Classification: Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Crustacea

Class: Maxillopoda

Subclass: Copepoda

Order: Cyclopoida

Family: Lernaeidae

Genus: Lernaea

Species: Lernaea sp.

Common Name : Anchor worm


Morphology: i. Anchor worms (Lernaea) can be seen with the naked eye

ii. In female behind mouth a well developed hold fast organ present

iii. The elongate neck and trunk carry the four pairs of legs

iv. If anchor penetrate in body, it never be removed

v. Tiny white-green or red worms in wounds

Figure: Lernaea sp.

Figure: Lernaea sp. on fish skin Figure: Lernaea sp. on fish gill

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Distribution:

Found almost all across the country

Common in closed water and open water fishes

Symptoms:



Localised redness

Inflammation on the body of the fish

Production Problems:

Breathing difficulties

General lethargy

Weight loss

Filthy flesh and outer side of fish

Even death occurs to fish

Treatment: Potassium permanganate

Salt dip

Formalin dip

Modern antiparasitics

Salt in the aquarium at 1 to 2 tablespoons may help to prevent

secondary infection

3. Leech (Piscicola geometra) Classification: Kingdom: Animalia

Phylum: Annelida

Class: Clitellata

Subclass: Hirudinea

Genus: Piscicola

Species: Piscicola geometra

Common Name : Leech


Figure: Piscicola geometra

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Morphology: i. Segmented worms

ii. Both oral and ventral sucker present

iii. Ventral sucker is only for attaching to the host

iv. Body surface divided into 102 annuli

Distribution:

Mainly occurs during winter

Found in both marine and freshwater environment

Symptoms:



Localised redness

Production Problems: Weight loss

Severe when the parasite remain attached for long time

Figure: Piscicola geometra on fish skin

Figure: Oral sucker of Piscicola geometra

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Treatment: Can be removed by hand using a fingernail or other flat, blunt object to

break the seal of the oral sucker at the anterior end of the leech

Common, but medically inadvisable techniques to remove a leech are to

apply a flame

Chemical such as alcohol, vinegar, lemon juice, insect repellent, heat

rub, or certain carbonated drinks

5. Ichthyophthirius multifiliis Classification: Kingdom: Animalia

Phylum: Ciliophora

Class: Oligohymenophorea

Order: Hymenostomatida

Family: Ichthyophthiriidae

Genus: Ichthyophthirius

Species: Ichthyophthirius multifiliis

Common Name : Freshwater ich


Morphology: i. Body oval to round but very elastic, 0.50 μm to 1mm in diameter

ii. Uniform ciliation

iii. A large crescent shaped macronucleus present (horseshoe-shaped

nucleus)

iv. The adult parasite moves slowly by tumbling but the immature forms

(tomites) are smaller, translucent, and move quickly

Figure: Ichthyophthirius sp.

Figure: Ichthyophthirius multifiliis on fish

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Distribution:

Indian major carps (Rui, Catla, Mrigel) are mainly affected

Most common and persistent diseases in fish Life cycle of Ichthyophthirius multifiliis is highly dependent on water

temperature, and the entire life cycle takes from approximately 7 days

at 25 °C (77 °F) to 8 weeks at 6 °C (43 °F)

Symptoms: Anorexia (loss of appetite, refusing all food, with consequential wasting)

Rapid breathing

Hiding abnormally

Not schooling (in schooling fish)

Resting on the bottom

Flashing

Rubbing and scratching against objects

Upside-down swimming near the surface

Infected fish have small white spots on the skin and gills


If not controlled, there is a 100% mortality rate of fish

Low quality of flesh and gill of fish

Treatment: Formalin (2000 ppm for 1 hour 15-40 ppm applied to ponds)

Malachite green (0.1-0.15 ppm or 0.05 ppm mixed with formalin 50 ppm

applied to ponds)

Heat treatment can be highly effective

Methylene blue

Chelated copper

Copper sulfate

Potassium permanganate

Quinine

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4. Round Worm (Anisakis sp.) Classification: Kingdom: Animalia

Phylum: Nematoda

Class: Secernentea

Order: Ascaridida

Family: Anisakidae

Genus: Anisakis

Species: Anisakis sp.

Common Name : Round worm

Parasite Type : Endoparasitic

Morphology: i. Need multiple host during life cycle

ii. Vermiform body plan, round in cross section and lack of segmentation

iii. Mouth located anteriorly, and surrounded by projections used in feeding

and sensation

Distribution:

Found in pond water fishes during winter

Uncommon where cetaceans are rare

Larval anisakids are common parasites of marine anadromous fish, eg.

salmon, sardine

Symptoms:

Loss of appetite

Abnormal movement

Figure: Anisakis sp.

Figure: Anisakis sp. in fish

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Allergic reactions to chemicals left by the worms in fish flesh

Weight loss

Treatment: Albendazole tablet or liquid

Conclusion: During the study period, a total of four ectoparasite species and one

endoparasite species were identified from the field study in Thakurgaon

district. The highest peak of parasite prevalence (%) was found in the host of

Labeo rohita in winter while the lowest was found in Catla catla in summer.

This might be due to stocking density, temperature along with other

physicochemical parameters as well as management practices maintained.

However, the total economic loss due to parasite diseases has been estimated

BDT 35,552.50 ha-¹ yr-¹ in Bangladesh³. Therefore, management of these

parasitic diseases should be given top priority to save the fish farm and

industry from this huge economic loss every year at farmer level.

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References: 1. Md. Abdus Sattar, District Fisheries Officer, Thakurgaon Sadar,

Thakurgaon-5100

2. Md. Latifur Rahman, District Fisheries Officer, Lalmonirhat (Previous DFO

of Thakurgaon)

3. "Parasitic Diseases and Estimation of Loss due to Infestation of Parasites

in Indian Major Carp Culture Ponds in Bangladesh", Md. Shirajum Monir,

Nazneen Bagum, Shafiqur Rahman, Mohammad Ashaf-Ud-Doulah,

Anuradha Bhadra, Shuvho Chakra Borty

4. "Wikipedia", the free encyclopedia

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