An experiment was conducted in a randomized block design to compare growth and economic performance between monosex and mixed-sex culture of red mud crab (Scylla olivacea Herbst, 1796) fed with trash ¢sh at 5^10% body weight per day in the mangrove tidal £at at Burigoaliny Union of Satkhira District, Bangladesh. The experiment had three treatments in triplicate each: (a) all-male culture, (b) all-female culture and (c) mixed-sex culture. Crabs of 80^120 g in size were stocked at a density of 0.5 crab m À 2 and cultured for 100 days. Speci¢c growth rates (SGRs) by weight and internal carapace width (ICW) in the all-male culture were signi¢cantly higher than those in the all-female culture (Po0.05), while SGRs in the mixed-sex culture showed no signi¢cant di¡erences from those in the all-male and all-female culture (P40.05). No sig-ni¢cant di¡erences in ¢nal mean body weight, ICW, daily weight gain, survival rate, gross and net yields were found among all the treatments (P40.05). The area of high water level with mangroves gave signi¢cantly better results in terms of feed conversion ratio, survival rate, gross and net yields than the area of low water level (P40.05). The experiment suggests that the all-female culture in the area of high water level with mangroves could be suitable in developing commercial pen culture of red mud crabs in Bangladesh.Mean values with di¡erent superscript letters in the same row were signi¢cantly di¡erent (Po0.05).Aquaculture Research, 2009, 40, 473^485 Growth and economic performance of Scylla olivacea Mst. M. Khatun et al. r 2008 The Authors Journal Compilation r 2008 Blackwell Publishing Ltd, Aquaculture Research, 40, 473^485 Ã Depend on size and sex: F 1 (female) 200 g^5 USD kg À 1 , D2 (egg bearing female) 120 g^1.14 USD kg À 1 , SM (small male) 200 g^0.86 USD kg À 1 , M (male) 250 g^1.43 USD kg À 1 , L (large male)2 USD kg À 1 . Mean values with di¡erent superscript letters in the same row were signi¢cantly di¡erent (Po0.05). Aquaculture Research, 2009, 40, 473^485 Growth and economic performance of Scylla olivacea Mst. M. Khatun et al.

Biochemical composition of seven small indigenous fresh water fishes namely Magur (Clarias batrachus), Shingi (Heteropneustes fossilis), Koi (Anabas testudineus), Foli (Notopterus notopterus), Royna (Nandas nandas), Taki (Channa punctatus) and Tangra (Mystus vittatus) from the Mouri river Khulna, Bangladesh was studied in order to evaluate their nutritional values. The mean value of protein, fat, moisture and ash content was found as 14.87 +/- 0.63, 7.90 +/- 1.91, 73.49 +/- 0.69 and 3.74 +/- 0.46% in C. batrachus; 17.34 +/- 0.51, 3.45 +/- 0.92, 76.06 +/- 2.24 and 3.15 +/- 0.25% in H. fossilis; 19.63 +/- 0.5, 7.79 +/- 2.73, 69.27 +/- 1.04 and 3.31 +/- 0.83% in A. testudineus; 18.30 +/- 0.79, 4.98 +/- 1.71, 72.68 +/- 1.08 and 5.82 +/- 0.82% in N. notopterus; 16.09 +/- 2.66, 7.34 +/- 0.49, 75.75 +/- 0.78 and 5.19 +/- .029% in N. nandas; 19.13 +/- 2.40, 4.55 +/- 1.18, 70.55 +/- 1.89 and 6.81 +/- 0.94% in C. punctatus and 15.62 +/- 0.32, 7.53 +/- 1.10, 73.99 +/- 3.13 and 6.50 +/- 0.63% in M. vittatus. Considering the result of the present study, it can be concluded that all the species are rich in food value.

Present state of the marketing and transportation of mud crab in Khulna region of Bangladesh was investigated through field survey from January to December 2001. Out of 9 upazillas in Khulna District mud crab business was found in 5 namely, Paikgacha, Koyra, Dumuria, Batiaghata and Dacope. The crab depots were located mostly near the highways and on the bank of rivers. The crabs landed at depots were harvested from various sources including the Sundarbans mangrove swamps, tidal rivers and canals, and black tiger shrimp ponds (ghers). Supply of mud crabs was round the year with a peak during rainy season. The total production was estimated to be 1872.28 tons in Khulna district in 2001 of which 1228.73 tons were males and 643.55 tons were females. The highest production of mud crab was found in Paikgacha (75.59% of the total production). The maximum average price was found for XL grade followed by F1 grade. The harvested crabs were transported to depots by small wooden boats. Trucks and buses were used to transport crabs at night when the ambient temperature was low in order to reduce mortality. The mortality rate during transportation was higher in summer. The domestic market of crab was poorly developed in this region because of high price, and social and religious prohibition among the Muslim. Most of the harvested crabs were marketed in the foreign country. Major importers of mud crab are China, Singapore, Hong Kong and Malaysia, Thailand and Taiwan.

Computer education is necessary for each of the sectors in a developing country like ours. Khulna is situated in the south-western region of Bangladesh. It is one of the important industrial cities in Bangladesh. In this paper, we made a study to identify and analyze the actual situation of computer education in Khulna city based on some questionnaire.