INTRODUCTION Blue transformations of fisheries sector have a prominent role to fulfill the world’s upcoming demand of protein and food security. Now a day’s fish farmers and aqua entrepreneurs are adopting intensive scale of fish farming practices and technologies to double their income and production. Because of these approaches India become global leaders in fisheries sector after china with total share of 7.58% in world’s production of fisheries (Anonymous, 2022). Advancement of fisheries industry will be very productive for its growth and expansion. Moreover, culture of valuable fish species under intensive systems like: Recirculatory aquaculture systems (RAS) and Biofloc technology will be productive in prospective of doubling fish farmer’s income. Modernizations in fisheries sector comes up with the introduction of Pradhan mantra matsya sampada yojanan (PMMSY). Moreover, RAS has an enclosed super intensive system intended to manage the high value fish species culture on higher stocking densities and the development of these kind aquaculture system and expansion bring about some serious aspects of pathogens occurrence during the culture Sergaliyev et al. (2017). These systems are often intensive in operation with high stocking densities where pure oxygen supplementation is provided for biofiltration to remove ammonia and dissolved carbon dioxide Summerfelt et al. (2015). Water physicochemical properties can be more unstable in RAS systems than in large ponds or flow-through systems, where stocking densities is lesser than RAS. Fluctuations in water quality parameters result in sudden disease outbreak or significant losses during the production cycle (Banrie, 2013). There is no hesitation that in RAS more sophisticated conditions were provided to fish for their better survival and production but this does not always commit pathogen free environment under water Sergaliyev et al. (2017). Climbing perch (Anabas testudineus) locally famous name is kabai or kawai in India (Fish Base, 2022). Kabai is a freshwater fish species and they have an ability to live under low oxygen conditions because of extra respiratory organs (Hughes et al. 1986). Besides this, climbing perch has thick flesh and delicate tastes (Muchlisin, 2013). Kawai contains high values of iron and copper essentially needed for hemoglobin synthesis (Saha, 1971). Mostly found in small rivers, canals, and swamps Hossain et al. (2021). In India climbing perch has a high customer demand with high value price (Singh et al. 2018). Because of its high value fish farmer in Haryana state of India prefer to culture kawai under intensive culture systems to gain up the high profit and production under confined water systems (RAS). Moreover, Haryana is the only state in India where first RAS system installed in India during 2016 at Sultan fish farm (TAAS, 2020). Besides this, Haryana is on second position in India during 2021 according to annual per hectare fish production (7000 kg/hectare) followed by Punjab (Anonymous 2021a, 2021b). On the other side, Recirculating aquaculture systems (RAS) enjoy many advantages. Advanced recirculatory systems represent only 4.5% of the total aquaculture production as compare to fish farming in pond culture dominating means of production. However, by the end of 2030, RAS will produce the near about 40% of the total aquaculture output. Europe poised to be a leader in water reuse systems (Lux Researcher, 2015). On the other hand, Physical achievements of department of fisheries under Pradhan Mantri Matsya Sampada Yojana already approved 2870 RAS units in India to till date (Anonymous, 2022b, 2022). However, the prevention and treatment of diseases in RAS is little bit challenging, as the pathogens spread throughout the system, and the addition of chemicals and antibiotics disrupts the microbiome of the biofilters Almeida et al. (2019). Under different circumstances with this flow-through aquaculture like: high fish and pathogen densities, limited medication possibilities, in many cases newer or less studied cultured species make recirculation facilities prone to disease problems (Koski, 2013). There is very limited study available on most common climbing perch disease outbreaks in RAS systems of Haryana. Therefore, in our one year surveillance, we tried to investigate the symptomatic infectious diseases outbreak in climbing perch under water reuse system (RAS) with different stocking densities and their preventive or therapeutic treatment measures. MATERIAL AND METHODS A cross question interview based survey was conducted throughout the Haryana state on different RAS farms to understand the most common water reuse farming problems (Table 5). Our main aim was to identify the symptomatic infections of climbing perch under distinct stocking densities. During this study, we have collected 20-40 pieces of climbing perch on each RAS farm and on the basis of fish farmer’s interrogation; we enlisted various symptomatic history and present situation of fish health. Moreover, we gathered this data from 14 distinct RAS farms of Haryana during 2021-2022 respectively. A survey questionnaire was used to extract the primary information regarding the stocking density of climbing perch under RAS tanks and the most common infectious symptoms, farmer’s ability to diagnose fish disease with the help of infectious symptoms, fish health management practices, rate of mortality and treatments (Fig. 1). RESULTS AND DISCUSSION All question queries were collected during survey time from different fish farmer’s of Haryana distinct districts regarding stocking density, disease outbreak and mortalities during their culture practices. Besides this, fish farmers and aqua entrepreneur were able to express the symptomatic observation in his/her own words. This was easily understandable. We used simple statistical methods to calculate the surveillance primary data such as frequencies and percentages. Pie and bar charts were used to depict the analyzed variables. Moreover, we applied our clinical pathological sciences of fisheries to identify the exact causative agent of infectious disease with the help of symptomatic identification signs on fish body. Occurrence of infectious symptoms and rate of mortality on RAS farms. During our survey program mostly RAS farmers of Haryana region reported that they have observed three to two different kinds of infectious symptoms in climbing perch or kawai within 6-8 months of culture period respectively. Significantly, 64.28% RAS farmers reported three types of infectious symptoms on fish body and 21.42% RAS farmers observed only two types of infectious symptoms in climbing perch (Table 1). On the other hand, 14.28% RAS farmers had never noticed any kind of infectious symptoms in climbing perch or kawai during 6-8 months growth cycle respectively (Table 1). The most common reported symptoms were like: red spots and ulcers on fish body like fluid in body respectively, brownish or white cotton like growth on the skin, gills and caudal region of body and tail and fin region start breaking with infections on bas of caudal region respectively. Moreover, highest average rate of mortality also observed in three types of symptomatic RAS farms 34.44% as compare to lowest average rate of mortality 20% find out in two symptomatic RAS farms respectively (Table 3). Frequency of stocking densities in RAS farms. Stocking density rate in RAS has a significant role in prospective of their growth and survival rate respectively. Moreover, during our one year surveillance, we observed that mostly RAS farmers prefer to stock Anabas test udineus on higher rate in their RAS 50000 litre tanks as compare to lower stocking density rate (Graph 3). On the other side, we observed that different RAS farmers has lower survival rate on higher stocking density and higher rate of infectious symptoms as compare to lower stocking density farms respectively. Most common treatment measures on RAS farms. In our survey we noticed mostly fish farmers prefer to use few sanitizers and disinfectants like: Benzalkonium chloride (BKC), KMnO4 and Iodine liquid or salt as a primary most common treatment measure on their RAS farms. Besides this, 72.42% RAS fish farmers prefer to treat their infected fish stock with antibiotics as a secondary most common feed based treatment in their fish diet respectively (Table 4). Moreover, use of herbal treatment was not so popular among the RAS farmers only 21.42% RAS farms prefer to use it as a treatment measure in case of infection. We observed that, use of CIFAX was only 57.14% on different RAS farms during infectious conditions as compare to BKC and KMnO4 respectively (Graph 4). Possible diseases diagnosis on the basis of clinical symptoms. As per clinical signs and farmer’s interrogations, we observed mainly possible chances of Epizootic ulcerative syndrome (EUS), Dropsy, Tail and fin rot disease, Saprolegniasis and Cotton wool diseases in climbing perch (Kawai) on mostly RAS farms except on 2 RAS sites where no infectious symptoms reported due to optimum stocking density practices as per our analysis (Table 5) (Kumar et al., 2022; Sergaliyev et al., 2017; John & George 2012; Robert et al., 2003). Table 5 depicts the RAS farmer’s site location, symptoms, treatment details and possible diagnosis diseases. In present surveillance, we analyzed that most of the RAS farmers of Haryana region doing their fish farming under this advance technology on very high stocking densities (10000-20000 fishes per 50000 litre tanks) with this impact they are facing infectious problems in their kawai (Anabas testudineus) stock respectively. Besides this, few RAS farmers have 0% rate of mortality due to (below 8000 fishes per 50000 litre tanks) optimum stocking densities (Table 5). Moreover, during the time of production cycle mostly farmers observing 3 types of symptomatic infections in their fish stock. On the other hand, BKC, KMnO4 and iodine are the most common treatment measures that RAS farmer had taken as primary measure to deal with pathogenic infections. Whereas, antibiotics and CIFAX has also comes on secondary priority of RAS farmers against these infectious diseases in Haryana.