Journal of Fisheries and Aquatic Science ISSN 1816-4927 www.academicjournals.com OPEN ACCESS Journal of Fisheries and Aquatic Science ISSN 1816-4927 DOI: 10.3923/jfas.2018.39.48 Research Article Reproductive Biology of the Threatened Menoda Catfish, Hemibagrus menoda (Hamilton, 1822) in the Kangsha River, Bangladesh 1,3 Ibrahim Shehu Jega, 1M. Idris Miah, 1Nahida Arfin Huda, 1M. Atiqur Rahman, 1Mst. Kaniz Fatema, M. Mahfujul Haque and 1M. Shahjahan 2 1 Department of Fisheries Management, Bangladesh Agricultural University, 2202 Mymensingh, Bangladesh Department of Aquaculture, Bangladesh Agricultural University, 2202 Mymensingh, Bangladesh 3 Department of Forestry and Fisheries, Kebbi State University of Science and Technology, Aliero, Nigeria 2 Abstract Background and Objective: Knowledge of reproductive biology of a fish species is particularly important for conservation and plays significant role in determining its sustainable management and suitability for culture. Aspects of reproductive biology of Hemibagrus menoda from Kangsha River Netrakona district, Bangladesh were studied to evaluate the on-set and period of spawning season and its reproductive potential, which were hitherto not reported. Materials and Methods: A total of 479 females and 400 males were collected using Gill nets and Seine nets from March, 2015 to February, 2016. Gonadosomatic index (GSI), fecundity and histology of the gonads were investigated. Regression analysis was used to estimate the relationships between fecundity and standard length (SL), fecundity and body weight (BW) and fecundity and ovary weight (OW). Results: The monthly mean GSI of female H. menoda started to increase from May to June and reached the peak (12.50±4.97) in July, indicating the peak spawning season of the fish. Mean fecundity estimates based on mature females was 77273.77±276.82 for fishes with mean length of 31.85±2.39 cm and ranged from 22954.99; 25.00 (cm) in May to 222171.8; 40.20 (cm) in July. Fecundity correlated positively with SL (Log F = 0.0135+4.399 log SL; r2 = 0.774), BW (F = 198.7 BW-47602; r2 = 0.805) and OW (F = 1066 OW+6124; r2 = 0.832). Based on histological data, yolk vesicle, premature and mature stages of oocytes were abundant in May, June and July, which further confirms the distinct spawning season of H. menoda from May to July. Conclusion: Hemibagrus menoda spawns once a year and the spawning season extends from May to July with a peak in July. This reproductive pattern helps in development of culture program and conservation of the species. Key words: Reproductive biology, GSI, fecundity, gonadal histology, spawning season Citation: Ibrahim Shehu Jega, M. Idris Miah, Nahida Arfin Huda, M. Atiqur Rahman, Mst. Kaniz Fatema, M. Mahfujul Haque and M. Shahjahan, 2018. Reproductive biology of the threatened menoda catfish, Hemibagrus menoda (Hamilton, 1822) in the Kangsha river, Bangladesh. J. Fish. Aquat. Sci., 13: 39-48. Corresponding Author: Ibrahim Shehu Jega, Department of Fisheries Management, Bangladesh Agricultural University, 2202 Mymensingh, Bangladesh Tel: +8801757480423, +2348039370546 Copyright: © 2018 Ibrahim Shehu Jega et al. This is an open access article distributed under the terms of the creative commons attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited. Competing Interest: The authors have declared that no competing interest exists. Data Availability: All relevant data are within the paper and its supporting information files. J. Fish. Aquat. Sci., 13 (1): 39-48, 2018 of broodstock and ultimately increasing the fish production11. INTRODUCTION Several studies have been conducted on various aspects of Fish reproductive biology is important in stock reproductive biology of fishes including sex ratio12-14, GSI15-17, assessment, fishery resource management, fisheries research fecundity18-20 and histology of the gonads21-23. Not until and profitable aquaculture practices. Knowledge recently, Jega et al. 24, studies on the reproductive biology of of the menoda catfish were hitherto not reported. In this regard, reproductive parameters such as sex ratio, onset and duration the purpose of this study was to provide the first hand of spawning season, maturity stages, ova diameter, fecundity information on some aspects of reproductive biology such as and histology of the gonads are particularly important for the GSI, fecundity and histology of the gonads of H. menoda conservation of fish species . Hemibagrus menoda, one of 1,2 from the Kangsha River, Bangladesh, so as to lay foundation the ray-finned, iteroparous and gonochoristic fishes, is among for the induced breeding, culture and eventual domestication the 8 species in the genus Hemibagrus belonging to the of this threatened fish species. family Bagridae. The species is characterized by having dark, vertical spots on its abdomen and is found in the river MATERIALS AND METHODS drainages in Bangladesh and northern India3. However, Hossain reported that due to natural and anthropogenic 4 induced changes, H. menoda have become critically Sampling site: Samples of H. menoda were monthly collected endangered. Moreover, the IUCN categorized the fish as near from the Kangsha River located at Jaria-Jhanjail, Latitude threatened. 25E0'41.10"N and Longitude 9E0 38'27.16"E in the Netrakona 5 district, Bangladesh. Spawning season refers to that part of the year in which various fish species get sexually active for spawning6. The expulsion of gametes from the body into the surrounding Sample collection: A total of 879 samples, including 479 water is called ʻspawningʼ, resulting in fertilization. females and 400 males were collected from the landing sites Knowledge of spawning activity is gaining more importance from March, 2015 to February, 2016. The specimens were as restoration efforts on large rivers to benefit endangered identified according to Rahman25 and Hossain26 and sexed species and fish diversity requires specific knowledge of when according to Norton et al.27. Fishing gears used in catching the fishes reproduce and the coincidence of environmental fish include Gill net, Seine net and by angling. The freshly conditions7. Spawning season can be determined by studying landed fishes were immediately iced at the sampling site, gonadosomatic index (GSI) of the species, external features of transported to the Aquaculture Laboratory of Bangladesh the ovaries, such as size and by histology of the gonads. The Agricultural University, Mymensingh, Bangladesh, where the GSI is often used to follow the reproductive cycle of a species experiment was conducted. The Total length (TL) of the over the year at monthly or less intervals and is a good specimens ranged from 31.55-45.37 and 35.48-43.43 cm for indicator of gonadal development of fish8. The GSI assumes females and males, respectively. that an ovary increases in size with increasing development by comparing the mass of the gonad with the total mass of the Gonad collection: The ventral side of the fish was cut and fish. Information on fecundity is also important in order to opened from the anus towards the lower jaw by using scissors evaluate a fish for its commercial potentials and to develop and the whole mass (fat tissues, stomach, liver, ovary, liver, numerical relationship between egg production and etc.) were removed and the gonads carefully detached from recruitment9,10. Moreover, to bring a new species in the other visceral organs by the use of needles and forceps. aquaculture, information of reproductive biology is essential The gonads were then cleaned with tap water and wiped with in case of mass seed production for supporting commercial blotting paper. The ovary weight (OW) was then taken before being kept in 10% buffered formalin (40% formaldehyde; Lab Grade-37% w/v) for study of fecundity and GSI. aquaculture in Bangladesh, a 5th leading aquaculture producing country in the world. Study of these parameters is necessary in order to arrive at some conclusions on the maturity and breeding season of this species which will aid in Determination of GSI: To determine the sexual maturity, the its propagation. Histological studies are the most reliable female GSI was calculated using the formula: technique to assess the reproductive strategy and tactics of fish species and also to determine peak period of spawning GSI  and to understand effective methods for increasing efficiency 40 Gonad weight (GW)  100 Body weight (BW) J. Fish. Aquat. Sci., 13 (1): 39-48, 2018 Fecundity estimation: Fecundity of H. menoda was into one cassette and labeled with a pencil accordingly. Standard histological processes involving dehydration, clearing, infiltration, embedding, trimming and blocking, sectioning, staining, mounting and observation of slides under a light microscope (XSZ-PW107) for identification of gametogenic cell types were performed. estimated for 169 matured females following the gravimetric method according to Nandikeshwari et al.28, Akter et al.29 and Islam et al.30. The external connective tissues were removed from the surface of the ovaries and blotting paper used to remove moisture from the surface of the ovaries. A sub sample of about 1-2 mm and 0.20 mg of the gonad was cut from the anterior, middle and posterior parts of the ovary and separately put in a Petri dish. The eggs were separated by using needle and forceps and counted with the aid of magnifying glass. Care was taken to sort the mature and immature eggs. The total number of matured and immature eggs of each ovary sub sample was sorted out and counted with the help of a needle and magnifying glass and estimated using the equation: F1  Statistical analyses: Mean GSI values of the female samples were computed monthly. Regression analysis was performed using MS Excel 2007 to estimate the relationships between fecundity and standard length, fecundity and body weight and fecundity and ovary weight. RESULTS Morphology of the gonads: Macroscopic examination of H. menoda during the 12 months study period showed that Gonad weight  Number of eggs in subsample Sub sample weight the gonads in female and male are bilobed, located in the dorsal portion of the body cavity, separated into two equal sizes, joined each other at the caudal region and formed a common duct at the base of uro-genital papillae. Ovaries in the developing and immature H. menoda are pinkish, slender and translucent and resemble immature testes in appearance. As they advance in maturity, they become pale green and greenish in colour and expand in length and diameter. Testes are thin, ribbon-like and somewhat segregated in developing (immature) fish but as the fish progress in maturity, they become creamier, whitish and serrated. By taking the mean number of three sub sample fecundities (F1+F2+F3), the absolute (total) fecundity FT, for each female fish was then determined using the formula as19: FT  F1  F2  F3 3 Relative fecundity determination: Relative fecundity is the number of eggs per unit length or weight of individual fish and was calculated as 31: GSI: The mean values of GSI ranged from 0.00±0.00 (December) to 12.50±4.97 (July) in female which showed distinct seasonal changes. The GSI started increasing in May, reached the peak in July and then abruptly dropped in August. Consequently, the GSI remained very low throughout the study period. The monthly variations in the mean GSI of female H. menoda is shown in Fig. 1. Relative Absolute fecundity  fecundity (Fr) Standard length or fish body weight or ovar y weight Estimation of fecundity-length and weight relationships: Relationships between absolute fecundity and standard length (SL), body weight (BW) and ovary weight (OW) were determined using the formulae32: F = a SLb, F = a+b BW and F = a+b OW, respectively, where ʻaʼ represents the intercept of the regression with y-axis and ʻ bʼ the slope of the regression line. Fecundity: The mean fecundity was 77273.77±276.82 for Histological examination of oocytes: Ovaries belonging to a fishes with mean SL of 31.85±2.39 cm and mean BW of 628.37±18.60 g (Table 1). The highest fecundity (222171.8) was in July from fishes with mean SL and BW of 40.20 cm and 1074.00 g, respectively. The lowest (22954.99) was in May from fishes with mean SL and BW 25.00 cm and 389.00 g, respectively. range of developmental stages were prepared for histological study by fixing in 10% buffered formalin for 3 days. They were then taken out from vials and cross sections from different parts cut and placed on tissue paper so as to absorb the moisture. Each cross section of an ovary was separately put terms of SL, BW and OW is presented in Table 2-4, respectively. Slight fluctuation was observed in the relative fecundity in terms of SL. However, lowest (903.47) relative fecundity was Relative fecundity: The relative fecundity of H. menoda in 41 J. Fish. Aquat. Sci., 13 (1): 39-48, 2018 Mean GSI 15 10 5 0 M A M J J A S O N D J F Month Fig. 1: Monthly variation in the mean GSI of female H. menoda The vertical bars indicate standard deviation Table 1: Egg counts of H. menoda collected from Kangsha River Netrakona Bangladesh (March, 2015-February, 2017) Month May May May June June July July July Mean±SE Range Fish No. SL (cm) BW (g) OW (g) GSI Absolute fecundity 10 09 10 21 20 34 29 36 31.50 25.00 33.40 28.50 26.70 40.20 29.50 40.00 31.85±2.3 25.00-40.2 665.00 389.00 478.00 400.00 336.00 1074.00 437.00 1248.00 628.37±18.6 336.00-1248.00 9.00 5.54 17.05 37.20 17.30 88.60 78.50 141.00 49.27±0.97 5.54-141.00 1.35 1.42 3.57 9.30 5.15 8.25 17.96 11.30 7.29±2.3 1.35-17.96 35869.59 22954.99 39869.59 70295.76 24025.37 222171.80 30821.26 172181.80 77273.77±276.8 22954.99-222171.8 SL: Standard length, BW: Body weight, OW: Ovary weight Table 2: Relative fecundity of H. menoda in relation to standard length (SL) Number of fish examined 40 19 19 24 28 39 Mean±SE Range Size group (SL, cm) Absolute fecundity Relative fecundity (SL, cm) 25.00-27.00 27.01-29.00 29.01-31.00 31.01-33.00 33.01-35.00 >35.01 31.85±2.39 25.00-40.20 23490.18 70295.76 30821.26 35869.59 39869.59 197176.8 66253.86±257.14 23490.18-197176.8 903.47 2510.11 1027.20 1120.75 1172.46 5633.62 2061.27±42.97 903.47-5633.62 Size group (BW, g) Absolute fecundity Relative fecundity (BW, g) 330.00-380.00 381.00-430.00 431.00-480.00 >481.00 468.25±0.89 356.00-1248 24025.37 46625.37 35345.43 143407.73 62350.97±58.56 24025.37-143407.7 67.677 114.980 77.590 298.140 139.60±2.37 67.67-298.16 Table 3: Relative fecundity of H. menoda in relation to body weight (BW) Number of fish examined 38 37 37 57 Mean±SE Range Table 4: Relative fecundity of H. menoda in relation to ovary weight (OW) Number of fish examined Size group (OW, g) Absolute fecundity Relative fecundity (OW, g) 38 37 37 57 Mean±SE Range 5.00-35.00 35.01-75.00 75.00-105.00 >105.01 49.27±1.26 5.53-141 28417.44 70295.76 126496.53 172181.80 99347.88±125.52 28417.44-172181.8 1420.87 1278.10 1405.51 1638.26 1435.69±6.11 1278.10-1638.27 observed in BW related fecundity (Table 3). Lowest (67.677) relative fecundity was recorded in the lowest (330.00-380.00 g) size group fishes while the highest (298.14) observed in smallest (25.00-27.00 cm) size group fishes while highest relative fecundity was enumerated in the largest (>35.01 cm) size group (Table 2). Deviations were also 42 J. Fish. Aquat. Sci., 13 (1): 39-48, 2018 250000 200000 Fecundity Log F = 0.0135+4.399 log SL (r2 = 0.774) F = 0.013SL4.399 2 r = 0.774 Where: F = Fecundity SL = Standard length 150000 100000 50000 The estimated coefficient of determination was 0.774 suggesting that 77.4% of the variation in fecundity was due to variation in SL. The slope (4.399) which is greater than 3 in the equation indicated that fecundity increases as the fish gets longer. 0 0 10 20 30 40 50 Standard length (cm) Fig. 2: Correlation between fecundity and standard length of Hemibagrus menoda 250000 200000 Fecundity Fecundity-BW relationships: The logarithmic relationship F = 198.7BW-47602 2 r = 0.805 between fecundity and BW of H. menoda gave a linear equation: F = 198.7 BW-47602; r2 = 0.805 (Fig. 3). The coefficient of determination showed that 80.5% variation in fecundity was due to variation in BW. A straight line through the origin would fit the points well which told that the number of eggs were directly proportional to the weight of the fish. 150000 100000 50000 0 0 200 400 600 800 1000 1200 1400 Body weight (g) Fecundity-OW relationships: In order to study this relationship, the fecundity values were plotted against the respective weight of ovaries as a scatter diagram (Fig. 4). Strong coefficient of determination (r2 = 0.832) was found between OW (X) and fecundity (Y). The relationship between fecundity and OW may be expressed using regression equation as: Fig. 3: Correlation between fecundity and body weight of Hemibagrus menoda 200000 Y = 1066x+6124 2 r = 0.832 Fecundity 150000 100000 F = 1066 OW+6124; r2 = 0.832 50000 and in logarithmic form as: 0 0 20 40 60 80 100 Log F = 1011+1.020 log OW (r2 = 0.832) Ovary weight (g) Fig. 4: Correlation between fecundity and ovary weight of Where: F = Fecundity OW = Weight of ovary H. menoda relative fecundity was in the largest (>481) size group. Results in Table 4 indicated that relative fecundity of H. menoda was less dependent on OW. The lowest (1278.10) relative fecundity in terms of OW was in the size group (35.01-75.00 g) while the highest (1638.26) fecundity was in the size group ($105.01 g). Variations in the histological features of H. menoda: The development stages of the oocytes in female H. menoda during oogenesis were identified over the 12 month study period (Fig. 5). Microscopic observations of the different ovary sections examined revealed different stages of development such as undeveloped oocytes (UO), early perinucleolar stage (EPNO), late perinucleolar stage (LPNO), cortical alveolar stage (CA), yolk vesicle stage (YV), early yolk granule stage (EYG), late yolk granule stage (LYG), pre-mature stage (PM) and the mature stage (M) (Fig 5). The UO and EPNO were observed in January and March samples and were found to be minute in size and difficult to recognize. Fecundity-length relationships: The relationship between fecundity and SL for H. menoda is presented in Fig. 2. The logarithm transformed fecundity and SL values were plotted in the scatter diagram and yielded a non linear (power curve) equation: F = 0.0135SL4.39. The logarithmic transformation gives a linear regression (straight line regression) of fecundity and SL of the fish as: 43 J. Fish. Aquat. Sci., 13 (1): 39-48, 2018 (a) (b) (c) (d) (e) (f ) (g) (h) (i) Fig. 5(a-i): Haematoxylin-eosin stained sections showing different developmental stages in ovary of H. menoda at 10x magnification sampled in (a) March, 2016, (b) April, 2016, (c) May, 2016, (d) June, 2016, (e) July, 2016, (f) August, 2016, (g) October, 2016, (h) December, 2016, (i) January, 2017. UO: Undeveloped oocytes, EPNO: Early perinucleolar oocytes, LPNO: Late perinucleolar oocytes, CA: Cortical alveolar stage, YV: Yolk vesicle stage, EYG: Early yolk granule stage, LYG: Late yolk granule stage, PM: Pre-mature stage and M: Mature stages yolk granules appeared deep pink with haematoxylin and eosin (June and July). At the end of mature (M) stage, vitellogenesis was completed, oocyte full-grown and yolk globules size increased (about 1060 µm). In the postvitellogenic oocytes large lipid vacuoles and yolk granules of the remaining oocytes degenerated and underwent atresia (August). Undeveloped oocytes (oogonia) predominate in the later stages (October) of oocytes development characterized by stem cells occurring singly. Subsequently the appearance of CA (December) which stained deeply with haematoxylin and eosin indicated the early stages of secondary growth development. The oocytes at this stage are often referred to as oogonia and after staining with haematoxylin-eosin, their sizes ranged from 17-54 µm. Oocytes in the mature stage were found to contain 4 bands of oocytes, LPNO, YV, LYG and M oocytes which predominates the May, June, July and August samples. The YV stage signals the onset of the vitellogenesis and initially appeared colourless on staining with haematoxylin and eosin. The YV stage contains several nucleoli which developed as minute bodies and progressively became enlarged in diameter of the oocytes (60-75 µm). At the LYG stage, oocytes increased concurrently with the advancement of yolk granules and the 44 J. Fish. Aquat. Sci., 13 (1): 39-48, 2018 11.5-14.0 cm for Mystus dibrugarensis, which is lower than that of H. menoda. Lower range was also reported by Karmakar and Biswas18 for Tetraodon cutcutia (Pisces: Tetraodontidae) from Meleng River in Jorhat district, Assam with minimum fecundity of 447.48 (TL = 5.86±1.19 cm) and maximum fecundity of 1540.08 (TL = 6.55±1.36 cm). Recently, lower minimum and maximum fecundity of 2230 (TL = 4.7-5.6 cm) and 8450 (TL = 7.7-8.6 cm) were recorded in Perthia ticto in the study of Gorai River19. Fecundity within a stock varies annually, undergoes long-term changes and has been shown to be proportional to fish size and condition21,39. Within a given species, fecundity may vary as a result of different adaptations to environmental habitats40. The mean fecundity of H. menoda was 77273.77±276.82 for fishes with mean length of 31.85±2.39 cm. This mean fecundity of H. menoda obtained in this study was higher than those obtained for Alburnoides sp., Perthia ticto and Securicula gora with average fecundity of 1722.92 (TL = 98.72 mm), 2586±700 and 23,860.12±4980.21, respectively31,41,42. It could be inferred that H. menoda is a highly fecund fish. Relative fecundity also contains information useful for comparing the reproductive strategies in fish and could be provided in terms of body and ovary weight2, 43. In this study, though highest relative fecundity was found in fishes belonging to the largest size group in terms of body weight and ovary weight, some fluctuations exist as it was observed that relative fecundity was not strictly dependent on body and ovary weight of H. menoda. The relative fecundity of 77.59 oocytes was found in 431.00-480.00 body weight group which is lower than the 114.98 oocytes found in the 381.00-430.00 weight group. Similar trend was found in relative fecundity in terms of ovary weight of H. menoda. Khan et al.37 reported 57.664 ova per ovary weight in Plotosus canius with average weight of ovary 21.287 g which was higher than the 14.022 ova per weight of ovary in a fish with ovary weight of 160.460 g. Therefore, this data somewhat conflicts the theory that relative fecundity is ovary weight dependent but corroborates with the theory that fecundity is affected by species, age, feeding, season and environmental conditions44. Fecundity in fishes is often correlated with length, body weight of fish and also with weight of ovary45. In this study it was found that fecundity increased with SL, BW and OW. Moreover, it was also found that in H. menoda, OW (r2 = 0.832) and BW (r2 = 0.805) are more responsible to increase in fecundity than SL (r2 = 0.774). Similar results have been reported for freshwater fishes Puntius stigma and Monopterus cuchia and concluded that the correlation of fecundity with gonad weight is more significant compared to that of fecundity with other body parameters46,47. Results from DISCUSSION The reproductive biology of H. menoda in terms of onset and duration of spawning through GSI, fecundity and histology of the gonads were studied as important inputs in the assessment and management of the fish stock. The GSI is often used to identify the gonadal maturity and spawning season of fish species. Examination of the ovary of H. menoda revealed a distinct relationship between GSI and gonad maturation in the fish. The high values of GSI in May, June and July obtained in this study indicates the spawning season of H. menoda. The highest value obtained only in July indicates one peak spawning season. The onset of spawning season in May observed for H. menoda coincides with the onset of rainy season in the region. It could be inferred that maturation of the gonads were influenced by the rainy season. This corroborates with Kiran15 that the GSI of gonads of cyprinid fish Salmostoma untrahi increased at rainy season whereas, lowest GSI was in winter. Recently, similar results were obtained in Labeo bata where high GSI values were observed from May to August and only one GSI peak in the month of June33. High GSI was recorded for Pomadasys jubelini in July to September34. The findings of this study agree with Al Mahmoud et al.35 who recorded higher GSI for Channa striata from March to July with a peak in July. Siddiquee et al.16 reported similar results in Channa marulius from Sylhet basin whereby highest GSI was obtained in July. Similarly Gupta and Banerjee36 stated that GSI in female Mystus tengara reached peak once a year during the month of July. Khan et al.37 mentioned that mature Plotosus canius (Grey-eel or Brackish water catfish) became available from April to August, the peak being July. Contrary to our findings, GSI of silver grunt, Pomadasys argenteus was highest in March and an additional small peak in October in the females38. The breeding period (GSI) of female Oreochromis niloticus exhibited several peaks in March, April, June and September21 suggesting that females breed more than once a season (partial spawning), which is contrary to our findings. Findings from this study showed that H. menoda is a single spawner and the breeding season expands from May-July with July being the peak. Fecundity estimation of fishes is vital to having information on the spawning season, reproduction potential and seed production capacity of the species concerned. In the present study, the minimum fecundity was 22,954.99 (SL = 25.00 cm) while the maximum fecundity was 222,171.8 (SL = 40.20 cm). Thus, the fecundity increased with increase in length of H. menoda. Bailung and Biswas20 reported minimum fecundity of 6,965±889.38 in fish of 6.5-9.0 cm and maximum fecundity of 12,338.57±1241.04 in length group of 45 J. Fish. Aquat. Sci., 13 (1): 39-48, 2018 this study agree with Agarwal45 in his study of fecundity of Schzothorax plagiostomus that a close correlation is usually expected between number of eggs and ovarian weight and volume. From the foregoing, it is evident that H. menoda is a highly fecund fish and its reproductive potential is quite high in comparison to other fishes probably due its large size and feeding habit as well as food productivity, temperature, salinity and genetic difference of the stock. Histological features of oocyte development stages were also studied to ascertain the breeding season of H. menoda. Histological observation revealed one spawning season in H. menoda, from late April to July, which corresponds to the monsoon season. In this study, oocytes maturation stages were classified into undeveloped oocytes (UO), perinucleolar oocytes (PNO), cortical alveolar stage (CA), yolk vesicle stage (YV), yolk granule stage (YG), premature (PM) and mature (M) stage. Al Mahmoud et al.35 and Milton et al.23 used similar classification for Channa striata and Channa gachua, respectively. In fish ovary, the premature (PM), yolk granule (YG) and mature (M) oocytes are generally observed at the most advanced stage of ovary when the fishes are ready for spawning. In this study, YG, PM and M oocyte stages were abundant from late April to July samples of ovary, indicating the spawning season of H. menoda. The occurrence of M stage oocytes was highest in July, indicating the peak breeding season. Current findings are similar to Erkmen and Kirankaya22 who observed that mature oocytes in Mirror Carp and Scaled Carp (Cyprinus carpio L., 1758) were first observed from the beginning of April until July that corresponds with monthly changes observed in GSI. The findings from GSI are in concurrence with the histological observations, further confirming the peak breeding season of H. menoda in July. Undeveloped oocytes (UO), EPNO and LPNO stage oocytes were abundant in October to January samples, indicating spent stage of ovary of H. menoda. SIGNIFICANCE STATEMENT This study discovered that H. menoda is a highly fecund fish and provides the first information on the spawning season (from May to July) of this species. 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Hossain, M.A.R., 2014. Habitat and Fish Diversity: Bangladesh Perspective. In: Advances in Fisheries Research in Bangladesh, Wahab, M.A., M.S. Shah, M.A.R. Hossain, B.K. Baman and M.E. Hoq (Eds.). Fisheries Research Forum, Dhaka, Bangladesh, ISBN: 978-984-33-6729-7, pp: 1-26. 5. IUCN., 2015. Red list of Bangladesh: A brief on assessment result 2015. IUCN International Union for Conservation of Nature, Bangladesh Country office, Dhaka, Bangladesh, pp: 1-24. 6. Haque, M.M., 2012. Fishes and Aquaculture Dictionary. 1st CONCLUSION Edn., Department Agricultural of University, Aquaculture, Mymensingh, Bangladesh Bangladesh, ISBN: 978-984-33-5829-5, pp: 25. The GSI revealed that H. menoda spawns once a year and the spawning season extends from May to July with the peak in July. Further histological examination of the ovaries of female H. menoda confirmed this finding as the GSI values increased with increasing histological changes. 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