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The current study provide the baseline information on the temporal (monthly) variations of condition through multiple functions (allometric, KA; Fulton's, KF; relative, KR) and prey-predator status through relative weight (WR) for Eutropiichthys vacha (Hamilton, 1822) from the Ganges River, northwestern Bangladesh over one year. The smallest individuals were 6.5 and 6.2 cm in TL, whereas the largest were 19.9 and 20.6 cm in TL for males and females, respectively. No significant differences were observed in the length frequency distribution, LFDs (p = 0.8152) for both sexes. KF was significantly correlated with TL for both sexes (p < 0.001) and KF was treated as the best condition factor therefore, well-being of E. vachaa. There was no significant correlation among TL vs KA, TL vs KR and TL vs WR for males and females, respectively. But BW showed highly significant correlations with all condition factors, i.e., BW vs KA; BW vs KF; BW vs KR, and BW vs WR (p < 0.001) for both sexes. Additionally, WR revealed no significant dissimilarities from 100 for males (p = 0.432) unlike females (p = 0.023), based on Wilcoxon signed-rank tests, suggesting that habitat was more suitable for males than females for food availability relative to predator presence. Moreover, this study assessed for the first time the effect of temperature and rainfall on monthly KF for E. vacha in the Ganges River. The Pearson correlation test found no significant relation between temperature and KF (r = 0.2226, p = 0.4868 for males; r = 0.2172, p = 0.4977 for females), but significant correlations were found between rainfall and KF (r = 0.6357, p = 0.0263 for males and r = 0.6983, p = 0.0115 for females). [ABSTRACT FROM AUTHOR]

Data and information are needed to avert the alarming decline and initiate conservation measures for three threatened fishes, Labeo boga (Hamilton, 1822), Nandus nandus (Hamilton, 1822) and Puntius ticto (Hamilton, 1822), from the Ganges River and surrounding ecosystems. These fishes are decreasing rapidly due to high fishing pressures as well as environmental degradation. This study furnishes the length-weight relationships ( LWRs), length-length relationships ( LLRs) and form factor ( a3.0) of these three threatened species from the Ganges River, northwestern Bangladesh. A total of 773 specimens from the three species and two families used for this study were caught by traditional fishing gear between April 2011 and March 2012. The analysis of covariance ( ancova) revealed significant differences between the sexes in LWRs for L. boga (P < 0.001), but not with the remaining species (P > 0.05). Furthermore, the LLRs were highly correlated ( r 2 > 0.983; P < 0.001), and ancova analyses additionally indicated that LLRs did not differ between sexes (P > 0.05). The calculated form factor ( a3.0) was 0.0111, 0.0159 and 0.0129 for L. boga, N. nandus and P. ticto, respectively. This study presents the first references on LWRs, LLRs and form factor for these three threatened species in Bangladesh. The results would be useful for further studies on the population assessment and sustainable conservation of the limited stocks in the Ganges River ecosystem. [ABSTRACT FROM AUTHOR]

This study describes the size at first sexual maturity, length-weight relationships (LWR) in relation to size at first sexual maturity, and Fulton's condition factor ( K F) of Eutropiichthys vacha in the Ganges River, northwestern Bangladesh. Sampling was done using traditional fishing gear including cast nets, square lift nets and conical traps during January and April, and July to December 2010. For each individual, total length (TL) was measured to the nearest 0.01 cm, and total weight (BW) was determined to the nearest 0.01 g. The gonadosomatic index (GSI) was calculated by the equation, GSI (%) = (Gonad weight in g/BW) × 100. The size at first sexual maturity of males and females was estimated by the relationship between gonadosomatic index and total length. A total of 583 specimens (289 males; 294 females) ranging from 8.30 to 27.00 cm TL and 3.16 to 159.50 g BW were analyzed. Sizes at first sexual maturity for male and female E. vacha were 13.15 and 14.00 cm TL, respectively. The analysis of covariance ( ancova) revealed significant differences in slope and intercept between early and late phases for males ( F = 4.532, P < 0.001) and females ( F = 21.984, P < 0.001). The K F was not significantly correlated with TL for males ( r s = 0.052; P = 0.378), but was highly correlated for females ( r s = −0.165; P = 0.005). This study establishes a strong base for monitoring changes in length at first sexual maturity attributable to high fishing pressures or other reasons within the Ganges and associated river ecosystems. [ABSTRACT FROM AUTHOR]

The present study aims to estimate the size at first sexual maturity and fecundity for female Gudusia chapra from the lower Ganges River, northwestern Bangladesh. A total of 250 female specimens, 3.60–13.70 cm in standard length (SL) and 1.00–43.60 g in body weight (BW), were collected during March–August 2006. The gonadosomatic index (GSI) for females was calculated by the equation, GSI (%) = (GW/BW) × 100. The size at first sexual maturity of females was estimated by the relationship between their gonadosomatic index and standard length. The specimen larger (≥8.00 cm in SL) than first size at sexual maturity was used for the estimation of fecundity. The size at first sexual maturity for female G. chapra was considered to be 8.00 cm SL in the Ganges River. The mean total fecundity was 20200 ± 6500 and ranged from 10800 to 36200. This study should be useful for fisheries biologists/managers to impose adequate regulations for sustainable-fishery management in the Ganges River and elsewhere in Bangladesh. [ABSTRACT FROM AUTHOR]

Length-weight relationships ( LWRs) were determined for Dermogenys pusilla (n = 75) and Labeo bata (n = 304) from the Ganges River, northwestern Bangladesh, collected between July 2013 and June 2014, using traditional fishing gear (e.g. cast net, square lift net and gill net). Total length ( TL) was measured to 0.1 cm and whole body weight ( BW) was taken to the nearest 0.1 g for each individual. The TL varied from 6.60 to 16.10 cm for D. pusilla and 7.90-25.20 cm for L. bata. The BW ranged from 1.20 to 10.90 g for D. pusilla and 4.70-167.30 g for L. bata. All LWRs were highly significant (P < 0.001), with all r 2 values ≥0.976. Moreover, the present study provides a new record of the maximum length (16.10 cm TL) for the D. pusilla female. The present study can assist in the management of these two endangered species in the Ganges River ecosystem. [ABSTRACT FROM AUTHOR]

This study describes the length–weight (LWR) and length–length (LLR) relationships for ten small indigenous fish species from the lower part of the Ganges, Bangladesh, namely Ailia coila, Amblypharyngodon mola, Aspidoparia morar, Clupisoma atherinoides, Eutropiichthyes vacha, Glossogobius giuris, Gudusia chapra, Lepidocephalus guntea, Mystus vittatus, and Puntius ticto. A total of 2142 specimens, representing 10 species of 5 families used for this study were caught by traditional fishing gear from March 2006 to February 2007. Standard length (SL), total length (TL) and fork length (FL) for each specimen were measured by digital slide calipers and each body weight (BW) was taken by a digital balance. The allometric coefficient b of the LWR was close to the isometric value ( b = 3.001) in G. giuris, although it suggested negative allometric growth in A. coila, A. morar, C. atherinoides, E. vacha, and P. ticto, whilst positive allometric growth in rest of the species. The results further indicated that the LLRs were highly correlated ( r 2 > 0.890; P < 0.01). To the best our knowledge, this study presented the first reference on LWR and LLR for most of the species in Bangladesh. [ABSTRACT FROM AUTHOR]