Fisheries and Aquaculture Journal
Open Access

Fish Farming Practices and Disease Occurrence in the Fish Farms of Dhanusha District, Nepal

Manish Yadav^*, Rahul Ranjan and Tapendra Bahadur Shah ^*Correspondence: Manish Yadav, Department of Agriculture and Forestry, Agriculture and Forestry University, Chitwan, Nepal, Tel: 9811856287, Email:

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Abbreviations

@: At the rate of; %: Percentage; AFU: Agriculture and Forestry University; AKC: Agriculture Knowledge Centre; AGDP: Agricultural Gross Domestic Product; CFPCC: Central Fisheries Promotion and Conservation Center; DADO: District Agriculture Development Office; FAO: Food and Agriculture Organization; FGD: Focus Group Discussion; FYM: Farm Yard Manure; GDP: Gross Domestic Product; Ha or ha: Hectare; INGO: International Non-Governmental Organization; Kg: Kilogram; LEE: Learning For Entrepreneurial Experience; MoALD: Ministry of Agricultural and Livestock Development; MOC: Mustard Oil Cake; MoP: Muriate of Potash; NARC: Nepal Agriculture Research Council; NGO: Non-Government Organization; NPK: Nitrogen, Phosphorous, Potassium; PACT: Project for Agriculture Commercialization and Trade; PMAMP: Prime Minister Agriculture Modernization Project; RB: Rice bran; RDF: Recommended Dose of Fertilizer; RM: Rural Municipality; SOC: Soybean Oil Cake; SPSS: Statistical Package for Social Sciences

Introduction

Aquaculture generally refers to controlled farming of aquatic organisms, like fish, mollusks, crustaceans and aquatic plants, etc. under controlled system of management. It involves rearing process such as regular stocking, feeding, pond management and protection from predators etc. that tends to enhance production thereby achieving significant economic returns. The stocked cultivated may be either individual or corporate ownership. And, this contribution to food security and economic growth if, includes only the rearing of fish and related species under respective ownership and systematic management is recognized as fisheries. Almost all fish produced are consumed as food in Nepal, recognizing it as the cheapest source of animal protein providing arrays of important nutritional and health benefits. It is acclaimed to be the prime source of lean protein and healthy fats in Nepal [1]. A nation with a wide range of agro-ecological types, Nepal is situated between the latitudes of 28°N and 84°E. Its terrain ranges from Southern plains that are less than 60 meters above sea level to the Himalayas, which are located above the latitude of 4800 meters above sea level. Consequently, Nepal has an agrarian economy that supports a diversity of agricultural methods and crop production, thereby leading to food security. Similarly, asserted that aquaculture may be able to utilize 7,900 km of irrigation canals in the country besides almost 6,000 river systems, streams, lakes, ponds, and other abundant water resources scattered across 500,000 hectares of Nepal. Aquaculture in Nepal provides 1.13% and 4.18%, respectively, to the overall GDP and AGDP. With a growth rate of 14.3%, which is greater than that of other agricultural sectors' growth rate of 7.17%, it is one of the sectors of Nepal's economy that is expanding the quickest. The majority of the “pond” or warm water fish production takes place in the southern part of the country-the Terai region, where 94% of the fish ponds are located. Bara, Dhanusha, Siraha, Morang, Sunsari, Kapilvastu and Rupandehi are the major districts where fish farming is done in large scale [2].

The Terai area has greater levels of both fish production and consumption. The yearly fish output is 104,623 Mt with a productivity of 5.32 T/ha overall, and 6734 Mt with a productivity of 5.20 T/ha alone in Dhanusha district. According to statistics from 2020–2021, there were a total of 2846 fish ponds, producing 6734 Mt. kg yearly. Within the district, a fish farm takes up 1295 hectares of space. Since the fish farming in Dhanusha is polyculture type and is getting more intensive in scale, relative occurrence and transmission of disease are also anticipated to rise. With growing area and a growing number of farmers engaged in commercial fish farming, it is one of the biggest fish farming districts of Nepal. The prime minister of the agriculture modernization project just proclaimed Dhanusha to be a "fish superzone" in the year 2016 [3]. They also stated that diseases if left unattended and uncured may cause huge loss to fish farmers and may decrease the overall fish yield. A number of governmental and non-governmental organization are working to uplift the fisheries sector in Dhanusha. Responsive planning for development of this sub sector is vital for increasing the production. Information on production and system and associated health management issues form a good base for planning and development in this sector. Considering the fact mentioned above, this study is designed to access the fish production systems adopted, and the underlying issues of diseases and pests in the fish superzone of Dhanusha. This study will help to identify the fish farming practices, occurrence of diseases and the existing health management practices adopted by the farmers in Dhanusha district [4].

Literature Review

Aquaculture in Nepal

Since ancient times, fish has played a significant role in Nepalese cuisine. Fish culture has historically made some localities and/or ethnic groups well known. For instance, the Majhi, Tharu, Kewat, Mallah, Mukhiya, Das, Kahar Lodh, Mahar, Magar Kumal, and Gupta tribes were among the indigenous people who relied on catching and eating fish as well as other aquatic creatures like ghunghi, crabs, and others from surrounding water sources for a long time [5].

A very recent development in Nepal, nevertheless, is commercial aquaculture. Using seeds of Indian major carp imported from India, it was started on a modest scale in ponds in the middle of the 1940’s. The introduction of the foreign species common carp marked the beginning of additional growth in the 1950’s (Cyprinus carpio). As a result of its breeding accomplishments in the 1960’s, carp monoculture was pushed, and the private sector was extremely impressed. The proportion of aquaculture in the nation's fish output is steadily increasing. However, significant improvement was made in the 1970’s with the introduction of three exotic Chinese carp species viz., grass carp (Ctenopharyngodon idella), bighead carp (Aristichthys nobilis), and silver carp (Hypophthalmichthys molitrix). Their ability to reproduce successfully in captivity has significantly advanced aquaculture in Nepal. Similar to this, effective trials of induced breeding of three economically significant indigenous large carps rohu (Labeo rohita), Mrigal (Cirrhinus mrigala), and catla (Catla catla) were conducted in our nation. This achievement served as the impetus for the development of the carp polyculture method, which is used to produce carp in ponds with seven other kinds of fish. Many farmers were motivated by this method since it significantly enhanced productivity per unit area and economic rewards. Beginning in the 1980’s, the aquaculture growth project, funded by the Asian Development Bank (ADB) and the United Nations Development Program (UNDP), directed the official or legal development of this technique. There are now 19 such development and research institutes operating around the nation for the development of aquaculture, which was recently established by the government of Nepal [6].

Over the years, pond aquaculture has been developed as the most viable and prominent aquaculture production system in Nepal. Carp polyculture in ponds is by far the most common and viable aquaculture production system adopted in Nepal which, in 2020/78 made up about 90 percent of the total pond aquaculture. Similarly, the share of pond fisheries is 88.12 percent of total national fish production of 83,623 Mt. The major part of the pond fish production takes place in the Southern part of the country the Terai plain, where 90.12 percent of the fish ponds are located. These ponds cover over 97 percent of the total water surface area and account for over 86 percent of the total pond fish production in the country. In the fiscal year 2020/21, the average fish yield from pond aquaculture was 5.40 tons/ha in Terai plain, that exceeded the national average of 5.3 tons/ha i.e., twice the average yield in the hills and mountains combined. The key to the growing popularity of the system in Terai is the warmer climatic conditions with suitable edaphology, which are conducive to faster and higher fish growth [7].

Approximately 232 of the 252 fish species in Nepal, many of which are tiny indigenous species (SIS), are the result of the finfish biodiversity. Numerous research support the claim that SIS normally provide communities around the country with substantially greater nutritional values. They can be found living up to the heights of up to 4,000 meters above sea level. However, Rohu, Labeo rohita, Catla/Bhakur, Catla catla, and Mrigal, Cirrhinus mrigala, are the three indigenous main carps that currently control the nation's aquaculture production system. Studies have also been conducted on the commercial production of three highly prized native cold water fish species, including the delicacy asala (Schizothorax spp.), katle (Acrossochielus spp.), and mahseer (Tor spp). Additionally, asala is a popular fish species for sun drying and processing across the Eastern highlands of Nepal, Mahseer is also well known for sports fishing. Genetic research and mass production have been pushed over all of the country's major river systems. Along with these, species like the Nile tilapia (Oreochromis niloticus), Java barb (Barbonymus gonionotus), and giant river prawn (Machrobrachium rosenbergii) have recently been studied to determine the viability and potential of their commercial production in Nepal with the help of neighboring nations [8].

Carp polyculture in ponds and lake enclosures; cage culture of herbivorous carps like silver and bighead carp; rice fish culture with common carp; and the comprehensive method of carp polyculture in ghols are the major aquaculture techniques used in Nepal. These aquaculture production methods are divided into groups based on the output and input levels of the production process. In all aquaculture production systems across the nation, farming practices have evolved over time from extensive to semi intensive to intensive [9].

Aquaculture has evolved as one of the fastest growing agricultural subsectors in Nepal. The current total national fish production is 104,623 Mt of which 20% contributes from capture fisheries while 80% is from aquaculture. Nearly 600,000 people now have direct jobs thanks to the expansion of aquaculture to 55 districts around the nation. The yearly per capita fish consumption has increased dramatically between 1981/82 and 2017/18, rising from 330 g to 3.39 Kg, but it is still quite low when compared to the global average of 16 kg per capita. The demand for fish is highest in the winter and at its lowest in the summer months of Jestha, Asar, and Shrawan. During the fiscal year 2018/19, domestic production occupied 89% and imported fish occupied 11% of the total national fish consumption whereas fish export remained negligible (Table 1) [10].

Table 1: Trend of fish production in Nepal (CFPCC, 2020).

The increment in rate demand for fish is greater than the rate of increase in fish production. People growing health concerns and nutritional awareness is the major reason for this increase in demand. People are consuming more fish than those past years but the level of production is not keeping up as demand rises. With an active involvement of private sectors is encouraged for seed, feed and implements supply etc., the government has confined its role in quality control. Fish is primarily marketed by the producer themselves from production site or through agent, contractor or whole seller. The import of fish declined by 28.08 per cent to 7,882 metric tons in the fiscal year 2019/20 compared to the previous fiscal year 2018/19 due to the unofficial blockade imposed by India. This trend of export and import is depicted in Table 2 [11].

Fisheries in national economy

Agriculture accounts to only 23.9 percent of total GDP of the nation while nearly two third of the population depends upon agriculture for daily livelihood which makes it a backbone of national economy. Currently, aquaculture contributes to about 1.13 percent of national Gross Domestic Product (GDP) and about 4.18 percent on Agricultural Gross Domestic Product (AGDP). Similarly, the economic growth of agriculture sector is 2.7% [12].

Fish production status in Dhanusha district

Dhanusha district is the hub for fish farming. It is because the district has the just climate and adequate temperature as well as water resources for fish farming. Dhanusha district is known for fish farming from ancient period of time; for having huge numbers of pond as well. Although a large number of farmers earn livelihood out of fish farming in this region, it is still in semi commercial level in many parts of the district (Table 2 and Figure 1). During the last seven years, the fish production is in increasing trend and area of pond is also expanding (Table 3) [13].

Table 2: Import and export value of fish and other aquacultural products.

Figure 1: Contribution of fish farming in AGDP and GDP (CFPCC, 2020).

Table 3: Fish production and productivity trend in Dhanusha district (MoALD, 2021).

Fish production systems in Nepal

Traditional fish farming in Nepal: In Nepal, traditional fishing has a really long history and is carried out by different indigenous methods viz. using cast net, gill net, loop, line and hook and basket. However, some unconventional fishing has emerged in recent years such as by using explosives, electricity and poison. This is potentially destroying the aquatic life indiscriminately. In the 1980’s, people engaged in fisheries were estimated to be about 80,000. The recent dramatic increase in the population engaged in capture fishery probably reflects the unemployment due to increased population in the country. Water bodies in Nepal are usually uncontrolled and unregulated for local access, and usually, the poorest most deprived people are known to harness nearby natural resources such as water bodies or forest for their livelihood. However, rivers and few natural water bodies have yet been managed in such a way and most remain a “free for all” A few lakes in the mid-hills have been stocked with cultivable carp for increased production as strategies to reduce the fishing pressure on thinly populated native species without losing the fisher’s employment and income opportunities, until measures for conservation practices of locally vulnerable species are developed [14].

Improved fish production technology: The aquatic microclimate is deliberately altered as part of ethical control and maintenance to promote fish output. This has been linked to pond aquaculture, the primary aquaculture method responsible for more than 95% of all aquaculture, while exotic carp account for up to 70% of this pond culture [15]. Similarly, Salau, et al., reported that improved fish production technology of fish was recognized with:

• Improved techniques in pond constructions and maintenance.
• Introduction of modern fish hatchery equipment.
• Provision of inlet and outlet device in ponds.
• Introduction of improved fish species for the optimum yield.
• Aerated containers for transporting the fingerlings to reduce stress and mortality.
• Techniques to improve water quality in fish.
• Fertilization and liming of fish ponds.
• Fish preservation and storage techniques.
• Prevention and control of fish disease.
• Controls of predators in fish pond.
• Techniques of hatchery and fingerlings production.

Similarly, with the increasing demand of land and water in fisheries, a colloquial approach of integrated farming is getting realized. The foundation of integrated farming is the idea that by combining two or more production systems, farm profits may be maximized [16]. The production of a greater variety of agricultural products, an increase in cash incomes, an improvement in the quality and quantity of agricultural products, a decrease in pollution, and a more effective exploitation of resources that would otherwise go unused are all benefits of this synergistic approach to agriculture that combines livestock and fish farming. Fish feed and pond fertilizers account for around 60% of the expenditures associated with fish cultivation. The well-considered integration of fish production with other suitable agricultural methods can significantly lower these expenses [17].

In order to fetch optimum fish growth and development, regular feeding, at required time is necessary. In general, the suggested supplementary feeding rate is: 14 kg/ha rice bran; 7 kg/ha oil cake; and 17 kg/ha grass and aquatic weeds. Daily feeding rates should be 4%-5% of the fish biomass in the water body, adjusted every fortnight based on observed fish growth [18]. The recommended rates of application for organic and inorganic fertilizers in an aquaculture pond are 3928 kg/ha per 6 months, along with goat and poultry manures as organic sources of fertilizers. Additionally, 560 Kg/ha of lime throughout the year is also recommended to buffer the soil pH and for healthy ponds. It is advised to apply an additional 250 kg/ha of lime throughout the growing season. In order to keep the algal biomass in the ponds, the water body must also be fed often with both organic and inorganic fertilizers as well [19].

The stances of pond management lie in maintenance of the production ponds or other ponds to an optimum condition that is conducive to successful growth and development of fish. According to an article published Michigan state university [20]. Some of the practices of pond management involves.

Pre stocking pond management such as management of aquatic weeds; drying or dewatering the ponds; pond sterilization, liming and manuring etc.

Post stocking pond management involves regular feeding of fish; maintaining proper water quality; liming and manuring; continuous monitoring for disease and/or discomfort symptoms, pond water test etc.

Contrarily, the traditional methods of fish harvesting include ring seine, stake net, Chinese dip net, cast net, shore seine, trammel net, mini trawls, gill nets, hook and line, traps and pots. however, the modern methods of fish harvesting include trawling, purse seining, gill net, hook and line mechanized, jigging and trolling lines, the most common being manual drag net.

An account of major fish diseases: Rodgers et al., concluded the fact that translocation of live aquatic species posed a greater risk of spread of infection than moving dead goods. The potential of pathogen transmission, disease invasion, and subsequent outbreaks of disease in the current aquaculture systems increases with the introduction of new exotic fish species to aquaculture. With the increased fish farming and intensification, the occurrence of different diseases is also increasing. Research conducted in the highland lakes and water bodies of Nepal, particularly in Trishuli, Begnas, and Mirmi, revealed that epizootic ulcerative syndrome was the most prevalent illness affecting common carp fish. The most troublesome parasite in carp production at the time, Trichodina, was found to cause issues in both private and public farms, including Begnas and Mirmi, as well as in the bulk of the fisheries domains across the nation. Fin rot, which causes fin degradation in common carp, silver carp, and bighead. Neodox was demonstrated to be very efficient when used with formalin (150 ppm).

It also described a number of problems with Nepali fish farms managing fish health, including a lack of assistance, a lack of technical know-how, poor treatment techniques, and a lack of suitable diagnostic facilities and the proper use of them. According to D. V. C. Jha et al., the central Terai area of Nepal, including Dhanusha, Mahottari, Sarlahi, Bara, etc. suffered greatly from fish infections. Following EUS in terms of frequency were argulosis, red spot, tail and fin rot, and nutritional issues. According to reports, winter and the first few weeks of summer were when diseases were most common.

Materials and Methods

Study area

The study was conducted across the fish superzone of Dhanusha district, Madhesh province, Nepal. Its elevation ranges from lower tropics, below 60 masl to 1000 masl. Dhanusha district covers an area of 1,180 km² and has a population of 838,084. The total arable area in the district is reported to be 76,531 ha. Commercial fish farmers and were taken under consideration for the survey and hence were pre-requisitely included in sampling. There were a total of 150 fish farmers registered in fish superzone, Dhanusha. Based on Roscole’s rule of thumb, 64 actively involved fish farmers were selected from all over the district through simple random sampling without replacement. Survey was conducted from February 2022 to April 2022.

Data collection

During the survey, primary data were collected based on semi structured pre tested interview schedule through personal interviews both on farm and during their office visits. The questionnaire emphasized on the socioeconomic background of the respondents; fish farm details, aquacultural practices, disease occurrence, fish production and storage after harvesting and marketing channel. Focus group discussion was conducted among the 15 farmers during checklist preparation as well as Key Informant Interview (KII) was conducted with the representatives of local stakeholders, head farmers, extension officers, local leaders and chief of the community based organizations etc. for the cross verification of the data. Simultaneously, secondary data were collected from PMAMP annual reports, research study, published articles, research papers and publications of NARC, AKC, FHRDTVC, CFPCC etc.

Data analysis technique

Both the qualitative and quantitative analyses were conducted using software like MS Excel and the SPSS (version 23). Descriptive analysis was employed for the variables like family size, educational status, size of landholding, various pond management practices like liming stocking, pond sanitation, fertilization and occurrence, severity and management of fish diseases etc. The obtained information was presented in the form of tables, graphs, charts and bar diagrams.

Scaling and indexing

Problems faced by respondents on fish production were ranked with the use of index. Scaling techniques, which provides the direction and extremity attitude of the respondent towards any proposition was used to construct index. The intensity of problems and measures were identified by using eight-point scaling technique using scores of 1.0, 0.8, 0.6, 0.4 and 0.2. The formula given below was used to find the indexing:

Where,

I_prob=Index value for intensity.
S_i=Scale value of i^th intensity.
F_i=Frequency of i^th response.
N=Total number of respondents.

On the basis of ranking of each problem by the respondents, final index value thus obtained conveyed the severity of each of the farmer's problems. Similar tactics were applied for scoring the severity of fish diseases as observed across the fish farms. Moreover, the aspects of strength, weakness, opportunity and threat of fish farming were also analyzed on the basis of ranking of responses thus obtained from the farmers.

Results and Discussion

Methods Broadcasting 9.20%   Heaping 90.8% Feed additives 87.50% 56   10.1 ± 8.4 Synthetic Fertilizers Urea 95.30% 61 33.1 ± 19.4 7.1 ± 8.3 DAP 95.30% 61 40.1 ± 16.8 10.5 ± 9.7 Others 15.60% 10     Liming Lime 99.40% 63 322.8 ± 156.2 5.2 ± 5.2 Methods Perforated sack placement 73.40% 47   Broadcasting 27.60% 17

Table 7: Status of liming and fertilizer management.

Figure 13: Correlation of fertilizer application and relative fish mortality.

Fish health and diseases: In this study, more than 50% of the farmers reported poor growth, odd swimming, and feed refusal. More than 25% of those polled reported seeing fish floating on the water. Fish are naturally active, therefore behavioral changes like body color, floating or sinking, anorexia or refusing feed etc., were the most obvious and frequent signs of sickness. From the results, it is evident that 76% of respondents were able to identify behavior of fish that were associated with deaths. However, only the respondents, as low as 35.93% were able to identify clinical signs of disease that were associated with deaths of fish. This clearly associated with insufficient knowledge and awareness of fish farmers about the specific fish diseases. With 47% of respondents reporting fish fatalities in their ponds, it was found that farmers were careful to note any deaths in their ponds. They claimed that the number of fatalities varied among farmed fish species.

Clinical signs of disease observed by fish farmers: According to the study, majority of the fish farmers (76%) reported some form of disease symptoms in their fish ponds. Farmers mentioned a number of diseases and conditions which they could recognized morphologically. The most prevalent clinical signs of disease were argulosis, learniasis and EUS. Other conditions like scale erosion, pop eyes, dropsy, mouth reddening, hemorrhagic eyes, rectal protrusion and malnutrition were also mentioned by the farmers but with lower incidences. This finding is in accordance to the one reported by Jha et al. (Figures 14 and 15).

Figure 14: On-farm reporting of various disease symptoms in fish.

Figure 15: Diseased fishes from on-farm observation in Dhanusha district: (A) Rohu (Labeo rohita) with argulus in body and fins; (B) Silver carp (Hypophthalmichthys molitrix) with Lernaea; (C) Naini (Cirrhinus mrigala) exhibited EUS on abdomen; (D) Fishes reported dead due to Asphyxiation; (E) Common carp (Cyprinus carpio) with dropsy; (F) Naini (Cirrhinus mrigala) suffering from malformation.

Status of disease severity on different fish species: According to the study, the most susceptible fish species to disease was naini followed by silver carp, rohu and bighead carp. Other species were also found susceptible but the rate was very low (Table 8).

Table 8: Status of fish affected by different diseases as reported by farmers during household surveys in Dhanusha.

In this regard, the study done by Jha et al., reported that central Terai region was the most afflicted by fish diseases, where EUS, argulosis, red spots and tail and fin rot were the serious diseases. The most susceptible species to diseases was silver carp followed by naini, bhakur, rohu and pangas in pond aquaculture of Bangladesh.

Status of fish mortality: Of the disease affected fishes, the mortality due to asphyxiation was found to be the highest, i.e., 346.15 ± 305.47 kg/ha. Species wise mortality was found to be not significant in the study areas.

However, in the study done by Hasan et al., mortality in pangas was found to be very high than the carp species. Similarly, black spot disease was found to be the reason for about 70% loss of fry of bighead and silver carp in Bardiya district in the study carried out by T. Gurung. He also reported Additionally, he stated that there was a 10%-15% annual loss in overall fish output and a 30%-40% annual loss in fish seed production due to different disease issues, which results in an annual economic loss of approximately Rs 1.5 billion in Nepal (Table 9).

Table 9: Status of fish mortality by different diseases in Dhanusha.

Seasonal variation of fish diseases: The majority of farmers (70.13%) claimed that infections were more common in the winter while asphyxiation and associated problems were more common in the summer, which increased the rate of mortality. Similarly, tail and fin rot were found to be predominant in winter season whereas argulosis was evident all-round the year. This finding concurs with that of Jha et al., i.e., the occurrence of fish diseases was higher in winter and on set of summer season than other times of the year. Similar conclusions were drawn by in a study conducted in pond aquaculture of Bangladesh (Figure 16).

Figure 16: Seasonal variation of fish disease in Dhanusha.

Fish disease management: In context of Dhanusha, farmers looked forward to other experienced farmers in order to ask for advice when for fish health management suggesting and disease treatment. It was found that 57.8% of the farmers “control” the disease whereas 26.5% of them “prevent” the diseases and 15.6% of the respondents “eradicate” the disease.

The foremost step to disease management, as practised was, pond water manipulation via recirculation (84.4%), net dragging (15.6%) and altered feeding and manuring (76.6%) that was reported to be an effective control of physiological disorders like asphyxiation and malnutrition. Next to it was the chemical approach viz., via use of lime, potassium permangnate, antibiotics, copper sulphate and pesticides. Additionally, chemicals like Super killer (5 ml/ha-8 ml/ha); Clinar (240 ml/ha) and Cifex (2.5 ltr/ha) were found to be effective against Argulus/Fin rot, Lernaea and EUS respectively. Similarly, tail and fin rot disease was reported to be successfully controlled by the use of granulated fabric dyes. However, more elaborate studies are recommended to ensure the efficacy of the dyes against fish diseases.

Regarding the curative aspects of fish diseases, formalin (150 ppm) was reported to be effective against gill rot. Similarly, it was reported that the combined efficacy of Ciphalexin (80 mg/kg of feed) and Kohrsolin-TH (900 ml/ha) was 97.7 percent for controlling EUS infection in carp species. However, the use of products sucha as DO Max, Aqua Fresh, Toximar, Clinar, Cifax, Totavet, and Malathion as treatment against fish disease, under the recommendations from local agro-veterinary vendors, was reported to be unspecified and/or unsafe (Figure 17).

Figure 17: Some common aqua medicines used by the farmers.

Ownership and Treatment of Fishing nets: Usage of drag nets (98.9%) for harvesting fish in the study areas was a common practice in Dhanusha district. The average net-sharing tendency among the farmers was 40.62%. Reported fish deaths were high in Dhnushadham and Mithila municipalities, where the highest % of shared nets was reported, but not statistically significant different (p>0.05 chi-square).

Net treatment was reported to be quite unrecognized practice in the study areas. This was due to two common reasons viz., lack of awareness of its importance and the large size of the drag net itself. However, all the farmers tend to wash and sun-dry the net after fish harvest, usually to facilitate carrying and storage. Some of the common practices of net treatment as reported are mentioned in Figure 18.

A significant association between mortality and sharing of nets was found in the study conducted. The use of salt and disinfectants for net treatment was indicated as being more effective than washing and sun drying in terms of preventing the spread of diseases (Figure 18).

Figure 18: Status of net treatment methods used by the respondents.

Status of extension services reaching the fish farmers

Sources of inspiration to initiate fish farming: The majority of respondents reported to rely for information regarding fish farming, upon fellow successful farmers (82.81%) followed by extension agents (9.50%) and from training (7.69%). Of all respondents, the majority of fish farmers in the study area undertook fish farming as inspired by successful farmers (61.75%), followed by the mass media (14.38%), 13.87% due to the establishment of PMAMP and other offices. Additionally, 10% of the respondents mentioned the problem of unemployment as their primary motivation for turning to fish farming.

Almost all the municipalities had well established fish farmers. They were found to be the icon for general people to start the fishery enterprise in the first place. Similarly, the establishment of offices like PMAMP (fish superzone); AKC and FHRDTVC with provision for subsidy and technical assistance had also attracted farmers into fish farming. Meanwhile, there also lied the condition of unemployment and lack of labours for agriculture in Dhanusha, thereby triggering fish farming in this district.

Disease extension: Government extension agents and Non- Governmental Organization (NGOs) support for disease management and prevention among fish farmers received rated extremely poor. In order to control illness, the majority of respondents relied on experienced farmers, while only a tiny % of respondents acknowledged the help of government agencies such FHRDTVC. PMAMP in general, aims to meet the needs of the farming community and other related stakeholders (such as service providers, farming entrepreneurs, rural youths, agricultural sector officials, agro service agencies, etc.) by making current information and services about PMAMP activities available to them through the various delivery channels that are close by. All of these stakeholders should use Agriculture Result Monitoring Information System (ARMIS) to help them make rational decisions to increase farm production and revenue while also receiving appropriate monitoring information from government and policy making officials. Still, rarely do farmers visit the PMAMP (fish superzone), AKC-Dhanusha or other government offices to report disease problems or seek technical guidance on disease management and production technology. This was potentially attributed to lack of cooperation among related institutions as well as lack of manpower and technology within the institutions. Similar results were shown in the study done (Figure 19).

Figure 19: Status of disease extension in Dhanusha.

Fish production and marketing

Fish production: Fish production also varied considerably with culture system and management factors. Average annual fish production from 64 respondents was 1561.81 Mt. Highest production of Chhadi (639.4 Mt) of rohu and naini was observed (Figure 20). This result is in proximity to the study done by Koirala et al., i.e., the maximum production of Chhadi fish (500 Mt) was obtained followed by that of silver carp (254.2 Mt) and bighead carp (220.7 Mt).

Figure 20: Production of cultured fish species (in Mt.).

Cost and return on fish farming: In this study, average cost of fish production was calculated per unit hectare of the pond considering both variable cost and fixed cost. Table 10 below suggest that the variable cost and fixed cost respectively account for 64.51% and 35.49% of total cost of fish farming. Cost of feed was found to be highest with 62.58% of total cost. Likewise, cost of pond construction was found to be highest among the fixed cost with share of 8.19 % of total cost.

Similar findings were obtained upon the study of feed economics, i.e., the expenditure on feeds alone contributes to more than half of the total cost of production. However, stated that the cost of feed alone constitutes only 37.46% of total cost of production in pond aquaculture system of Dhanusha district (Figure 21 and Table 10).

Figure 21: Component-wise cost % of farm inputs in study area, 2022.

Table 10: Status of cost and return from fish farming in Dhanusha.

Marketing channel used by the fish farmers: The research indicates that the farmers didn't employ any particular marketing channels. The study found that the majority of farmers purchase agricultural inputs from local markets (57.8%), distant markets (32.4%), as well as from India (9.2%). The open border with India allowed for the more affordable importation of equipment, fertilizers, and feed supplies. However, the majority of the inputs were purchased domestically.

Similar to this, local farmers in the study region sold their catch at daily or weekly fish markets. The majority of the harvest was sold in the local markets and within the district to various wholesalers, retailers, or directly to the consumers using various marketing strategies. Large quantities of Chhadi fish are also sold simultaneously at far off markets like Lahan, Sarlahi, Biratnagar, Dharan, and Kathmandu. According to the study, producer-wholesaler-consumer channel sales accounted for 54.70% of sales made by the respondents, followed by producerwholesaler- retailer-consumer channel sales (28.10%). It was discovered that the dhalta system and unpredictable fish marketing channels were the main market problems in this district's fisheries industry. Moreover, similar conclusion was found, stated that it was extremely difficult for smaller farmers to compete in the market due to trader monopolies, open borders, road restrictions and a lack of market intelligence (Figure 22).

Figure 22: Fish Market Channel of Dhanusha district.

Farmers’ satisfaction from fish farming: According to the study, it was reported that 50% of the farmers were satisfied due to the fish farming while only 37.20% of the respondents expressed to be satisfied due to extension services from the government offices. Furthermore, young entrepreneurs reported higher level of satisfaction than older ones. This might be due to higher adaptability to competition among the youths. However, an elaborative study is needed to be done to fully understand this tendency (Figure 23).

Figure 23: Farmers' satisfaction from fisheries.

SWOT analysis of fish farming in Dhanusha district: The aspects of strength, weakness, opportunity and threat of fish farming involves strength and weakness as internal factors whereas opportunity and threats as external factors. According to the study, greatest strength of fish farming in Dhanusha was reported to be the higher price and profitability of fish followed by suitable agro climate and utilization of marginal lands onwards. Similarly, the foremost weakness thus reported was Market mafia such as dhalta system and inappropriate pricing followed by unavailability of quality inputs and so on. Additionally, the best opportunity reported was availability of marginal lands followed by potential for production of quality seeds and feedstuffs, women empowerment via employment in fish farming and promoting research and development. Meanwhile, the foremost threat reported was uncertain shortage of feeds and fertilizers followed by disease related productivity dip, leading to market shutdown due to potential pandemic and lastly, climate change with potential natural disasters (Table 11).

Table 11: SWOT Analysis of fish farming in Dhanusha district.

Conclusion

Fish farming in Dhanusha was mostly traditional pond based carp polyculture, which was controlled by young and educated farmers. The supply of feeds and fertilizers was found to be less than recommended at greater stocking rates. Argulus, Lernaea and EUS were found to be serious fish disease whereas naini and silver carp were the most susceptible fish species in Dhanusha district. However, highest damage of fish was reported due to asphyxiation followed by EUS. The most popular method of disease control was liming and/or pond drying. Potash, salt, and numerous other insecticides including Malathion were also claimed to have been used. The average production of fish in the study areas was estimated to be 4.49 Mt/ha with the B/C ratio of 1.36. The major strength of fisheries herein, was the availability of suitable climate and topography, whereas the chief weakness was the lack of knowledge and poor extension services in relation to fish production and disease management in Dhanusha district.

Acknowledgements

The authors are grateful towards Agriculture and Forestry University (AFU) Rampur, Chitwan for funding the research and prime minister's agriculture modernization project, Project Implementation Unit (PIU) fish superzone, Dhanusha for their vital support and cooperation. We are also thankful to the respondent farmers in the study area as well as all the helpful hands.

Conflict of Interest

The authors declare that there is no conflict of interest.

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