Freshwater aquaculture in the Indian Sundarbans: expansion, challenges, and climate change adaptation.

A decadal outlook for global aquaculture

An year long experimental multi-species farming of Indian major carps (IMC) and minor carps was conducted with varied stocking densities in 15 earthen ponds (0.08 ha) to develop a suitable farming model. The IMC group included Catla catla, Labeo rohita and Cirrhinus mrigala at 35:40:25 ratio while minor carp and barb (MCB) group included Puntius gonionotus , Labeo fimbriatus and Puntius sarana at 40:35:25 ratio. Fingerlings were stocked in five density combinations (treatments) as: T1 - IMC at 8000 ha-1, T2 - IMC at 8000 ha-1 + MCB at 4000 ha-1, T3 - IMC at 4000 ha-1 + MCB at 4000 ha-1, T4 - IMC at 4000 ha-1 + MCB at 8000 ha-1 and T5 - MCB at 16000 ha-1. Survival of all species in both groups showed inverse relation with their stocked densities. T4 with IMC and MCB at 4,000 and 8,000 fingerlings ha-1, respectively, formed the ideal density with 28.8 and 76.0% higher yield realisation compared to T1 with only IMC and T5 with only MCB group, respectively. All multispecies treatments having MCB group as major component yielded higher fish biomass than those with IMC group. Such results indicated potential of multispecies farming system to increase production in seasonal ponds and water bodies retaining lower water level.

An year long experimental multi-species farming of Indian major carps (IMC) and minor carps was conducted with varied stocking densities in 15 earthen ponds (0.08 ha) to develop a suitable farming model. The IMC group included Catla catla, Labeo rohita and Cirrhinus mrigala at 35:40:25 ratio while minor carp and barb (MCB) group included Puntius gonionotus, Labeo fimbriatus and Puntius sarana at 40:35:25 ratio. Fingerlings were stocked in five density combinations (treatments) as: T1 - IMC at 8000 ha-1, T2 - IMC at 8000 ha-1 + MCB at 4000 ha-1, T3 - IMC at 4000 ha-1 + MCB at 4000 ha-1, T4 - IMC at 4000 ha-1 + MCB at 8000 ha-1 and T5 - MCB at 16000 ha-1. Survival of all species in both groups showed inverse relation with their stocked densities. T4 with IMC and MCB at 4,000 and 8,000 fingerlings ha-1, respectively, formed the ideal density with 28.8 and 76.0% higher yield realisation compared to T1 with only IMC and T5 with only MCB group, respectively. All multispecies treatments having MCB group as major component yielded higher fish biomass than those with IMC group. Such results indicated potential of multispecies farming system to increase production in seasonal ponds and water bodies retaining lower water level.

Aquaculture is a rapidly growing fisheries sector in India with an annual growth rate of over 7%. Freshwater aquaculture contributes over 95% of the total annual aquaculture production of 5.77 million t. Technologies of induced carp breeding and polyculture of the three Indian major carps (Catla catla, Labeo rohita and Cirrhinus mrigala) as well as ‘composite carp culture’ with the addition of three exotic carps (Hypophthalmichthys molitrix, Ctenopharyngodon idella and Cyprinus carpio) in ponds and tanks brought about perceptible upward shift in freshwater aquaculture production. Of late, the sector has been witnessing diversification with the inclusion of medium and minor carps, catfishes and murrels. Andhra Pradesh and West Bengal are the top producers of freshwater fish through aquaculture. System diversification has resulted in optimum productivity of 3-6 t ha-1 yr-1. Public and private carp hatcheries produce around 40 billion fry. Fish requirement by 2020 is expected to touch 15 million t, of which around 9 million t would need to come from freshwater aquaculture. Input-related, social and environmental constraints of aquaculture in India need to be tackled through horizontal and vertical expansion, technology as well as climate change mitigation and adaptation, for sustainable development.

Haemorrhagic septicaemia (HS) is a bacterial disease causing severe economic losses in freshwater aquaculture. The present study aimed to isolate, identify, and characterize its pathogen responsible for disease outbreaks and mortality in Indian major carps from ponds in the Kolleru Lake region, India through monthly sampling over eight months. Infected fish exhibited hemorrhages on the body, around the eyes, mouth, ventral surface, fins, and caudal region. Blood, kidney, liver, spleen, and gill tissues were processed for microbiological, biochemical, and molecular analysis. DNA from the isolates was amplified via PCR using primers specific to Aeromonas hydrophila, yielding a ~760 bp product, confirming the pathogen’s presence. This finding establishes A. hydrophila as the causative agent of haemorrhagic septicaemia in Labeo rohita and Catla catla. The results underscore the frequent and significant mortalities in culture ponds caused by bacterial diseases such as haemorrhagic septicaemia and abdominal dropsy, highlighting the need for targeted disease management strategies in aquaculture.

Post-harvest loss of mrigal (Cirrhinus cirrhosus), catla (Catla catla), rohu (Labeo rohita) and kalibaush (Labeo calbasu) in different distribution channel of Noakhali district, Bangladesh were observed during the month of January 2015 to April 2015. Sensory evaluation method was adopted in order to gather information about quality loss of fish and existing handling condition at different stakeholder level. The observed fish were fresh at fisherman level but as the day progress along with temperature variation fish started losing quality and most of their quality found lost at retailer level. Fisherman supplied fish to beparies at 5% quality loss, further 10%, 20% and 22% loss was observed through aratder, retailer and consumer respectively. DPs varied with the month basis, compared to January–February the DPs were higher in March–April which indicates that temperature rise cause more quality loss of fish. Most of the fishes crossed DP 3.0 at retailer level because of long term exposure to open air coupled with unhygienic condition of markets. Different sizes baskets were used for transportation of fish with or without icing. Live fishes were transported with water in gallon or drum and they could retain their shelf lifelong time than that of dead fish or fish with no icing condition. The unsold fishes were preserved in refrigerator and re-icing was adopted by 70% retailer. The ice ratio of fish: ice was 1:1 in March–April and 2:1 in January February. The more quality loss of fish the more ice was used. Bad handling practices due to transportation and in markets also caused quality deterioration of some fishes. Usually post-harvest loss of fish is not taken under the consideration which eventually because economic loss coupled with food insecurity but proper steps to reduce loss can compensate the post-harvest fish loss. Keywords: post-harvest loss, Indian major carps, defect points, handling practice Cite this Article Palas Chwakravorty, Amir Hossain, Saiful Islam, Mahabubur Rahman, Abdulla-Al-Asif, Hafzur Rahman. Post-harvest Handling and Quality Loss of Indian Major Carps in the Distribution Channel of Noakhali District, Bangladesh. Research & Reviews: A Journal of Bioinformatics . 2019; 6(1): 9–19p.

This study was conducted to assess the aquaculture potential of the freshwater prawn Macrobrachium rosenbergii (de Man, 1879) with the Indian major carps (Catla, Catla catla; Rui, Labeo rohita and Mrigal, Cirrhinus mrigala) and silver carp, Hypophthalmichthys molitrix in northwestern Bangladesh. Further, the effect of the culture system on overall production and economic feasibility was evaluated. A 3×2 (treatment×replicate) experimental setup was conducted using six earthen ponds measuring 100 m2 each for a culture period of six months from September, 2007 to February, 2008. The treatments were as follows: T1 was stocked with only carps (catla, rohu, mrigal and silver) at the 3000 (catla), 2000 (ruhu), 3000 (mrigal) and 2000 (silver) ha-1; T2 and T3 were stocked with catla and silver carp were 3000 and 2000 ha-1, respectively; and additionally M. rosenbergii (juvenile) was stocked at 15000 and 20000 ha-1 in T2 and T3, respectively. All the ponds were subjected to the same fertilization treatment. Fish were fed twice per day at a rate of 5-12% of the prawn and fish body weight. The net weight gain of catla and silver carp were 69.08±11.63 and 108.67±15.00 g in T1, 61.76±12.58 and 98.80±17.05 g in T2, while 58.11±12.51 and 93.09±14.84 g in T3, respectively. The mean individual weight of harvested prawn was significantly higher in T2 (14.61±02.06 g) than T3 (14.04±01.83 g) (P<0.05). Also the survival rate of prawn was higher in T2 (74.15%) than T3 (69.25%) (P<0.05). The net production of prawn was higher in T3 (1141.28±46.35 kg ha-1) than T2 (964.54±25.53 kg ha-1), but the specific growth rate was significantly higher in T2 (2.07%) than T3 (1.99%) (P<0.05). Higher profit was obtained in T3 (35682.18 Tk ha-1) than T1 (8537.53 Tk ha-1) and T2 (30801.56 Tk ha-1); however, cost-benefit ratio (CBR) was significantly higher in T2 (3.19) where stocking densities of prawn was 15000 ha-1 than T1 (2.92) and T3 (2.47). The results of this experiment indicate that the polyculture of the freshwater prawn with the Indian major and Chinese carp present a more profitable venture which is more economically feasible than the monoculture of the freshwater prawn.DOI: http://dx.doi.org/10.3126/on.v9i1.5735

Chapter 5: Law and regulation

Freshwater aquaculture in India mainly relies on three Indian major carps, with rohu (Labeo rohita) being the most important species in polyculture systems. Quality hatchery seed production plays a vital role in enhancing aquaculture production. However, unorganised and poorly managed broodstock in hatcheries affect the seed quality leading to economic losses for farmers. These challenges can be tackled through the establishment ofscientifically managed brooders. Developing an optimal female-to-male ratio for brooders requires maintenance of a large number of individuals for an entire year, as sex can only be determined at the maturity stage only. To address this issue, the current study developed a molecular marker and a Loop Mediated Isothermal Amplification (LAMP) assay for early gender determination, enabling the identification of the gender of rohu, even at the fingerling stage. This marker would enable the hatchery professionals and farmers to maintain an optimal male-to-female ratio from the early stage, leading to better broodstock management, reduced inbreeding and enhanced seed quality and quantity, which would ultimately benefit the aquaculture industry and promote sustainable fish farming practices in India Keywords: Early gender determination, LAMP, Quality hatchery seed, Rohu, Sex-specific marker

An experiment on polyculture of mahseer with Indian major carps at same stocking density was carried out for a period of 10 months from February 1 to December 1, 2004 in six experimental ponds. There were three treatments with two replicates each. Treatment 1 was designed with catla (Catla catla), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala), treatment 2 with catla (Catla catla), rohu (Labeo rohita) and mahseer (Tor putitora) while treatment 3 with catla (Catla catla), rohu (Labeo rohita), mrigal (Cirrhinus mrigala) and mahseer (Tor putitora). Mahseer of the treatment 2 was introduced instead of mrigal of treatment 1 and 50% of mrigal was replaced with mahseer in treatment 3. The stocking density in all the treatments was 30 fish/decimal (7500 fish/ha). The feeds were supplied at the rate of 3-7% of the body weight of fish. The gross and net productions recorded were 5362.78 and 5188.64, 5431.42 and 5262.32, 5357.11 and 5528.74 kg/ha/yr in treatments 1, 2 and 3 respectively. Though there was no significant difference (p>0.05) among the three treatments using ANOVA but the production in treatment-3 was slightly higher than treatments 1 and treatment 2. However, there was no negative effect of mahseer on the growth and production of Indian major carps. So, it can be concluded that polyculture of mahseer with Indian major carps (catla, rohu and mrigal) can be done in ponds.DOI: http://dx.doi.org/10.3329/pa.v18i2.18194 Progress. Agric. 18(2): 175 - 182, 2007

The effects of different ova diameters on hatching, growth and survival of fry of the common carp (Cyprinus carpio var. communis, Cyprinidae) and Indian major carps viz.Catla catla, Labeo rohita, Cirrhinus mrigala (Cyprinidae) were examined. The four female brooders of different weight and size of each of Cyprinus carpio var. communis, Catla catla; Labeo rohita and Cirrhinus mrigala were collected. The highest mean ova diameter was observed in (Cyc 4) 1.235 ± 0.006 mm, (Cc 4) 5.386 ± 0.098 mm, (Lr 4) 4.94 ± 0.167 mm and (Cm 4) 4.95 ± 0.091 mm; highest fertilization rate (Cyc 4) 92.48%, (Cc 4) 85.42%, (Lr 4) 89.64%, (Cm 4) 86.49%; highest hatching percentage (Cyc 4) 82.32%, (Cc 4) 79.67%, (Lr 4) 81.28%, (Cm 4) 80.17% and highest survival (Cyc 4) 75.57%, (Cc 4) 76.36%, (Lr 4) 80.51%, (Cm 4) 68.35% respectively. The specific growth rate was also found highest in Cyprinus carpio var. communis (Cyc 4) 5.94%, Catla catla (Cc 4) 5.62%, Labeo rohita (Lr 4) 5.81% and Cirrhinus mrigala (Cm 4) 5.86% in fry of brooders having maximum weight. The direct relationship of ova diameter to fertilization rate, hatching, survival percentage and the specific growth rate of Cyprinus carpio var. communis, Catla catla, Labeo rohita and Cirrhinus mrigala were recorded. However, after the fifth week, the growth rate of spawn reduced in all the groups and was least at the end of the eighth week.

The present study deals with stakeholder-driven implementation of pen culture for raising of fish seed for Culture-based fisheries (CBF) in Chamta, a floodplain wetland, in Gangetic plains through polyculture of Indian Major Carps (IMCs) Labeo catla, Labeo rohita and Cirrhinus mrigala with Small Indigenous Fishes (SIFs) Labeo bata, Systomus sarana and grass carp, Ctenopharyngodon idella in co-management mode. In the first polyculture trial IMCs and minor carps were cultured in 4 High Density Poly Ethylene (HDPE) pens (0.1 ha each) at a stocking density of 25 Nos. m−3 in equal numbers for 90 days. In the second polyculture trial IMCs were cultured with grass carp at a density of 25 Nos. m−3 in 4 HDPE pens in the ratio of 1:1:1:2 for 90 days. The same set of pens was utilized for both trials during different times of the year. Net yield of 682.3 ± 20.6 kg and 413.9 ± 21.7 kg per pen was achieved through polyculture of IMCs and SIFs and polyculture and for IMCs and grass carp, respectively. The survival percentage varied with species and culture period with overall survival of 77 (IMCs + minor carps) to 85% (IMCs + grass carp). Polyculture was economically feasible with a BC ratio of 2.01 for IMC and SIFs and 1.88 for IMC and grass carp. All the seeds produced in the pens were released to the wetland as input for CBF. The study indicated the potential of grass carp fishery in macrophyte-infested wetland. The species could attain 1.5–2 kg in 6 months and up to 3–3.5 kg weight within 1 year, utilizing macrophyte resources of the wetland. SIFs S. sarana and L. bata were observed to attain maturity in pens. The study indicated pen as an economically feasible technology to boost CBF in the wetland. The cultivation of SIFs through pen culture and CBF can enhance their production while alleviating pressure on their natural populations. Integrating pen culture using diversified species will promote sustainable fisheries management in these floodplain wetlands.

Biodiversity of an aquatic ecosystem and its management is considered to be one of the leading concerns of enabling sustainable use of natural resources. Fishes have a wide impact on the existence and influence on other organisms in their habitat. In the present study of fish diversity and its abundance in Nakki Lake, Mount Abu was studied in the weather cycle of 2018-19 in ten different sampling sites. The findings show the precise number of fish, population density, homogeneity and species dispersion patterns in Nakki Lake. To estimate the number of fish population in the lake, quadrat sampling method was used owing to certain constraints by the department of forest, as Mount Abu falls under the categoriy of eco-senstive zone. The lake supports around twelve species of fishes which are Aorichthys seenghala, Mystus cavasius, Carassius auratus, Catla catla, Cirrhinus cirrhinus, Garra gotyla, Labeo gonius, Labeo rohita, Puntius sarana, Puntius ticto, Gambusia affinis and Heteropneustes fossilis. Out of these dominating fishes are Labeo gonius, Labeo rohita, Catla catla, Heteropneustes fossilis. The result shows that the lake supports fish diversity and the lake habitat is condusive to the growth of thriving population of fish as well as other aquatic species. The other method such as electrofishing could not be carried out since the lake is leased for boating facilities for tourists and fetches high renumeration, which contributes to the revenue of the town.

Aims: The present study was carried out to determine the concentration of heavy metals and to evaluate whether there are any serious toxic effects of the widely exposed heavy metals namely arsenic (As), lead (Pb) and chromium (Cr) in different tissues of two commercially important cultured fish Rohu (Labeo rohita) and Catla (Gibelion catla)
 Study Design: The study was designed based on Randomized Block Design (RBD) to avoid all kinds of possible biases as well as for ensuring the representation of different fish farms. Three replications were maintained to deal with the possible errors caused by sampling.
 Methodology: Lead (Pb), Arsenic (As) and Chromium (Cr) were analyzed in a graphite furnace (GBCGF 3000 with Zeeman background corrector) with an auto sampler using Atomic Absorption Spectrophotometer (AAS). ALP (alkaline phosphates) activity of liver, Kidney and muscle was assayed using the standard method stated by Garen and Levinthal (1960) [1]. ATPase enzyme activity was determined to follow the standard method stated by Post and Sen (1967) [2]. During each month, ten individuals of the targeted two species each incorporating with three replications were collected from four intended fish farms, with a total of 240 fishes in the study period.
 Results: The obtained results stated the highest concentrations of all heavy metals (except arsenic) were recorded in Rohu fish with no significant difference with the other investigated fish species Catla. Organ wise heavy metal concentrations in Rohu (Labeo rohita) fish showed that Lead (Pb) concentrations were higher in all organs compared to other investigated heavy metals. The recorded values of Pb in gills, livers, kidneys, and muscles were 0.021, 0.021, 0.028 and 0.008 ppm respectively. In case of Arsenic (As), the highest concentration was recorded in kidneys while the Chromium (Cr) showed higher accumulation in the muscles. While it comes to Catla (Gibelion catla) fish, similar results were demonstrated where Lead (Pb) concentration was the highest and Chromium (Cr) concentration was lowest. Among all the three heavy metals, the accumulation trend of Arsenic (As) was found highest in gills of Catla (Gibelion catla) but Lead (Pb) and Chromium (Cr) were accumulated in high concentration in kidneys of the same species. The average concentration of different heavy metals in the two investigated fishes were lower than the standard recommended value (0.01ppm) except for Arsenic (As) in Catla (Gibelion catla) which was 0.013ppm. Enzymatic activities like ATPase and ALP were recorded highest in kidney tissue and the lowest in muscle in case of both fish species.
 Conclusion: Even though the average values of Arsenic in Catla (G. catla) fish was slightly higher than the recommended value suggested by WHO [3], the concentration is lower in edible part muscle which in turn indicates that the cultured Rohu (L. rohita) and Catla fishes in the Chattogram region are safe for human consumption.

Large quantities of fish offal and mulberry leaf are generated globally. The present study aimed to understand their potential utilization in aqua diet formulation, after proper fermentation, as raw materials to replace fish meal in Indian major carp (Labeo rohita) compounded diet. Fish offal meal (FOM) and mulberry leaf meal (MLM) were used in a 2 × 3 factorial design, to evaluate (i) two different fermented mixtures with the inclusion of both FOM and MLM or only MLM and (ii) to replace three different level of dietary fishmeal: 50, 75 or 80 %. An indoor trial, to evaluate diet intake and digestibility and an outdoor trial to evaluate growth performances were impended in Indian major carp fingerlings. The results showed that FOM and MLM are promising raw materials that can be successfully used in the formulation of diet for the Indian major carp. Specifically, the addition of a proper amount of MLM in the fermentation of FOM produced a fermented mixture that could successfully replace up to 80 % of FM in the diet formulation.