Md. Yeamin Hossain

Life history traits of the Monsoon River prawn Macrobrachium malcolmsonii (Milne-Edwards, 1844) (Palaemonidae) in the Ganges (Padma) River, northwestern Bangladesh

The Monsoon River prawn, Macrobrachium malcolmsonii (Milne-Edwards, 1844), is one of the dominant benthic species in the Ganges River. Our study describes some biological parameters including sex ratio, length–frequency distributions (LFD), length–weight relationships (LWR), and relative-condition (Kn ) factor of M. malcolmsonii in the lower part of the Ganges River, northwestern Bangladesh. A total of 502 specimens of the ranges 3.54–11.76 cm total length and 0.50–15.20 g body weight were analyzed in this study. Sampling was done using traditional fishing traps (Kara) during the period from March to October 2010. The overall sex ratio showed no significant differences from the expected value 1:1 (χ 2 = 0.20, p = 0.157), and there was no significant difference in the LFD between the sexes (p = 0.460). The allometric coefficient b for the LWR indicated isometric growth (∼3.00) in males and negative allometric growth (<3.00) in females. Kn showed significant variation (p < 0.01) between the sexes, with better performance by females (1.027 ± 0.107) than males (0.968 ± 0.130). To our knowledge, this study presents the first comprehensive description of life-history traits for M. malcolmsonii from Bangladeshi waters. Our data should be useful for the sustainable management of this prawn fishery in the Ganges River basin of Bangladesh and neighboring countries.

OVER-WINTERING GROWTH PERFORMANCE OF MIXED-SEX AND MONO-SEX NILE TILAPIA Oreochromis niloticus IN THE NORTHEASTERN BANGLADESH

The study was conducted to assess the over-wintering growth performance of mixed-sex and mono-sex male tilapia, Oreochromis niloticus. The experiment was carried out with two treatments each with three replicates for a period of 6 months from October 2012 to March 2013 in the Field Laboratory Complex, Bangladesh Agricultural University. In the first treatment (T 1 ), mixed-sex tilapia was stocked in 3 ponds with a mean initial weight of 4.80±0.18 g. In the second treatment (T 2 ), mono-sex male tilapia was stocked in another 3 ponds with a mean initial weight of 4.81±0.20 g. Fish were fed at the rate of 6% of fish body weight at the beginning of the experiments, then the feeding rates were gradually reduced to 2% for the third month and finally increased to 3% for the rest of the period. Water parameters in terms of temperature, dissolved oxygen, pH, transparency, alkalinity, ammonia and nitrite were within the range of fish farming. After 6 months of culture period, mono-sex male tilapia attained a significantly (P 0.05) difference of food conversion ratio and survival rate (%) values between the treatments. The benefit-cost ratio was calculated as 1.17 and 1.43 for mixed-sex and mono-sex male tilapia, respectively. The results suggested that it is possible to successfully culture tilapia during the winter period in Bangladesh, and the culture of mono-sex tilapia is more profitable due to its higher growth rate.

THREATENED FISHES OF THE WORLD: Cirrhinus reba (Hamilton 1822) (Cypriniformes: Cyprinidae)

The threatened Reba carp Cirrhinus reba is one of the foods high in nutritional value in Asian countries, including Bangladesh, India, Nepal and Pakistan. However, natural populations have been declined due to overexploitation and various ecological changes in its natural habitats leading to an alarming condition and deserving high conservation importance. This paper recommends actions for the conservation of the remaining isolated population of C. reba in Asian countries.

Condition, length–weight and length–length relationships of the silver hatchet Chela, Chela cachius (Hamilton, 1822) in the Old Brahmaputra River of Bangladesh

The silver hatchet chela, Chela cachius (Hamilton, 1822), is a cyprinid freshwater species, commercially important for both subsistence and artisanal fisheries in Bangladesh. This study describes the length–weight relationship (LWR), length–length relationship (LLR) and the condition of this minnow species from the Old Brahmaputra River in Bangladesh. In this study, 12 monthly samples totalling 2400 specimens (1172 male; 1228 female) collected from November 2004 to October 2005 were used to conduct this study. For each individual, the total length (TL), fork length (FL) and standard length (SL) as well as body weight (BW) were measured. The overall sex ratio showed no significant difference from the expected value of 1:1 and the analysis of covariance (ANCOVA) revealed no significant difference between LWRs of male and female for the pooled data over a year. Parameters of LWRs of combined gender varied monthly with high coefficients of determination (r 2 > 0.751; p < 0.001). All the LLRs (SL vs. FL, FL vs. TL and SL vs. TL) exhibited strong correlations (r 2 > 0.886; p < 0.001) and ANCOVA analyses further indicated that LLRs did not differ between males and females. The relative-condition factors with regard to both months and SLs varied in all gender groups. Females maintained similar mean condition throughout life and showed more plumpness than both males and combined genders in all months. Finally, the results should be useful for the sustainable management of this minnow species in Old Brahmaputra River and adjacent water-bodies.

THREATENED FISHES OF THE WORLD: Eutropiichthys vacha (Hamilton, 1822) (Siluriformes: Schilbeidae)

River catfish Eutropiichthys vacha is one of the foods high in nutritional value in Asian countries. However, natural populations have seriously declined or are on the verge of extinction due to over-exploitation and various ecological changes in its natural habitats, leading to an alarm- ing situation which deserves high conservation attention. This paper suggests conservation measures that should be taken into account to- wards the preservation of the remnant isolated population of E. vacha in Asian countries.

THREATENED FISHES OF THE WORLD: Labeo bata (Hamilton, 1822) (Cypriniformes: Cyprinidae)

Minor carp Labeo bata is an endangered fish species in Bangladesh. This fish is one of the commercially and nutritionally valuable food fish in Asian countries including Bangladesh, India and Pakistan. L. bata is an important target species for small scale fishermen in Bangladesh who use a variety of traditional fishing gears. However, natural populations are seriously declining due to loss of habitat, siltation in the river basin, indiscriminate killing of fry and fingerlings, water pollution by industrial and domestic waste, agrochemicals and overexploitation. This paper recommends the sustainable conservation measures of this endangered fish species in Bangladesh and neighboring countries. CODEN RIBAEG ISSN 1330-061X (print), 1848-0586 (online)

THREATENED FISHES OF THE WORLD: Heteropneustes fossilis (Bloch, 1794) (Siluriformes: Heteropneustidae)

Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi 6205, Bangladesh Department of Fisheries Management, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh Faculty of Fisheries, Kagoshima University, 4-50-20 Shimoarata, Kagoshima 890-0056, Japan Department of Zoology, Anando Mohan College, National University, Gazipur 1704, Bangladesh

THREATENED FISHES OF THE WORLD: Botia dario (Hamilton, 1822) (Cypriniformes: Cobitidae)

Bengal loach Botia dario is a valuable food fish in South Asian countries including Bangladesh, Bhutan, India and Nepal. However, the wild popula- tion is declining due to heavy harvest, habitat loss and its ecological chang- es. This paper suggests actions for the conservation of the lasting isolated populations of B. dario in Asian countries.

Threatened fishes of the world: Wallago attu (Bloch and Schneider, 1801) (Siluriformes: Siluridae)

The Asian Silurid catfish Wallago attu is an endangered species. Populations are declining due to over-exploitation, pollution and environmental degradation. Law enforcement to ban destructive fishing practices should be enhanced for the conservation of the populations.

Population biology of the pool barb Puntius sophore (Hamilton 1822) (Cyprinidae) in the Padma River, Bangladesh

The cyprinid pool barb Puntius sophore (Hamilton 1822) is widely distributed in freshwaters of Southern Asia. We determined some basic population biology parameters of P. sophore including sex ratio, length-frequency distributions (LFDs), length-weight relationships (LWRs), condition factors, relative weight and fecundity. Samples were collected monthly during July 2010 to June 2011 from the Padma River, Bangladesh. The overall fish sex ratio significantly differed from the anticipated value of 1:1 (p < 0.001) in favour of female specimens (1: 1.31). Females were significantly larger and heavier than males (p < 0.001). The LWRs showed isometric growth in both sexes; however, with clear monthly variation. Fultons condition factor was found to be significantly correlated with the total length (TL) and body weight (BW) and the most suitable among the studied condition factors for interpreting population well-being. Total fecundity varied from 1488 to 18708 (5682 ± 3703), while the relative fecundity...