Meter Ham
Ham antenna question?
Could you cut or lenghten a 2 meter ham (144 to 148 Mhz) broadcast antenna to make it broadcast FM (88 to 108 Mhz)?
If so is there an equation for determining the length needed?
Not a good idea in general. I have no idea what type of antenna it is. Generally the antenna elements should be longer for the lower frequency (100 MHz). But even for the simplest antenna design you shouldn’t lengthen the element(s).
You can build simple antennas or buy from Radio Shack. The simple ones are 1/4 wave whip w/ ground plane, dipole (1/2 wave), and folded dipole. 1 wavelength = (3e8 m/s)/frequency.
You also need to know the impedance you need, which can be 50, 75 or maybe 300 ohms.
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Growth and Yield Performance of Endanger Singi, Heteropneustes Fossilis (bloch) Under
Introduction
H. fossilis (Bloch) is an indigenous stinging cat fish of South-East-Asia which is locally known as
Singi or Shing in different parts of Bangladesh. It is not only recognized for its delicious taste and market value but is also highly esteemed from nutritional and medicinal properties of view. The species is very high content of iron (226 mg/100 g) and fairly high content of calcium compared to many other freshwater fishes (Saha and Guha 1939). Due to high nutritive value the fish is recommended in the diet of the sick and the convalescents. Being a lean fish it is very suitable for people for whom animal fats are undesirable (Rahman et al. 1982). It is a very hardy fish who can survive for quite a few hours outside the water due to presence of accessory respiratory organs. This fish was abundantly available in our open water system of Floodplains, canals, beel and haors of Bangladesh. But due to over exploitation and various ecological changes in its natural habitat; this species is threatened. Indiscriminate destructive practices have caused havoc to aquatic bio-diversity in Bangladesh (Hussain and Mazid 2001). H. fossilis is one of the threatened fish in Bangladesh (IUCN, Bangladesh 2000). Considering its status of threatened, high market value and high consumer demand it is essential to develop an appropriate breeding, nursing and rearing technology of fry and fingerlings of singi. This technology will helpful to prevent the fish from being extinct and at the same time this delicious tasty fish will be available for the rural people. This fish has enormous aquaculture potential and it could be easily grown in ponds and small ditches. In order to do so, a huge quantity of fingerling would be required for monoculture technology of H. fossilis.
To provide the fish farmers both financial and nutritional support, it is essential to develop a monoculture technology comprising of singi. A little Information on the growth performance of singi under conventional monoculture technology is developed. The present study was undertaken to evaluate and overall impacts on the growth and production of fish in this monoculture system in Bangladesh.
2. Materials and methods
2.1 Study area and experimental design
The experiment was conducted at the different rearing ponds of non government Brahmaputra Fish Seed Farm, Puliamary, Shambhugonj, Mymensingh, Bangladesh. Pond reared, feed trained Singi fingerlings of average weight (± SD) 4.6±0.04 g were stocked into nine 0.06 ha ponds with an average depth of 1.1±0.31 meter on 1 September 2006. Three replicate ponds were randomly assigned to each of three treatment densities (74100, 98800 and 123500 fingerling/ha). The pond dyke was covered with netting and culture was tested in 2006 to 2007.
2.2 Pond preparation, stocking and fertilization
The ponds were dewatered, freed from aquatic vegetation, predatory animals, exposed to full sunlight and had a well designed system of inlet and outlet. After drying, quicklime (CaCO3, 250 kg ha-1) was spread over the pond bottom. All the ponds were filled with ground water. Seven days subsequent to liming, the ponds fertilized with organic manure (cowdung @ 2470 kg/ha).
2.3 Supplementary feeding
In order to meet up the increasing dietary demand, a commercial fish feed, Saudi Bangla purchased from Saudi-Bangla Industrial Company, Bangladesh. Proximate composition of the feeds was analyzed according to AOAC (1984) method, nitrogen free extract (NFE) by subtraction (Castell and Tiews 1980). Proximate composition (% dry matter) of the supplementary feeds (crude protein, crude lipid, crude fiber, ash and Nitrogen-free extract) of experimental feeds was 32.21%, 7.70%, 10.19%, 18.16% and 31.74%, respectively. Feeds were supplied to the fish at the rate of (3-5) % of their total biomass twice daily in the morning and afternoon commencing from the first day of stocking. Daily ration was adjusted by estimating the standing crop once in each fortnight by random sampling of the stock.
2.4 Water Quality Parameters
Physico-chemical parameters of pond water were monitored fortnightly between 9.00 and
10.00 h. Water temperature was recorded using a Celsius thermometer and transparency (cm) was measured by using a Secchi disc of 20 cm diameter. Dissolved oxygen and pH were measured directly using a digital electronic oxygen meter (YSI, Model 58, USA) and an electronic pH meter (Jenway, Model 3020, UK). Total alkalinity was determined by titrimetric method (Clesceri et al.1989).
2.5 Estimation of growth, survival, production and feed utilization
Harvest was conducted 1 April through 5 April, 2007. Total yield (kg) and number of Singi
harvested from each pond were recorded. Twenty percent of the population from each pond was randomly sampled and individually weighed and measured for total length (TL) with the help of a portable sensitive balance (Model HL 400 EX) and a measuring scale until they attained marketing size. Growth in terms of weight, Relative growth (RG), Average daily gain (ADG), Specific Growth Rate (SGR) and Food conversion ratio (FCR) was estimated. SGR and FCR were calculated according to Brown (1957); Castell and Tiews (1980) and Gangadhara et al. 1997, respectively. After seven months, the table size fishes were harvested by repeated netting, followed by draining or drying the ponds. Both the number of species were counted and weighed. Survival (%) and production (number/ha) of fingerlings were then calculated and compared among the treatments.
2.6 Economic analysis
The cost analysis was in terms of hectare to maintain a standard unit. In calculating the cost, the variable (only material inputs) was used. The gross return from the pond was the sale proceeds of the total fish production.
2.7 Analysis of experimental data
The data were analyzed through one way analysis of variance (ANOVA) using MSTAT followed by Duncan’s New Multiple Range test to find out whether any significant difference existed among treatment means (Duncan 1955; Zar 1984). In all statistical analysis, the difference was considered to be significant when P0.05) among different treatments during the study period. Mean Secchi disk transparency differed significantly (P0.05). There were no significant variations (P>0.05) in the value of dissolved oxygen among the treatments. Total alkalinity was found to be highest in treatment T2 and lowest in treatment T3 and differ significantly (P
The growth and production of fishes in term of gain in weight under three treatments were investigated and monitored fortnightly. The results obtained are presented in table 2, which indicated that the growth in terms of weight showed much variation in each treatments and continued till final harvesting. During the investigation, final weight of H. fossilis was recorded to be 73.26±2.55, 53.72±4.14 and 37.28±4.88 g in treatment T1, T2 and T3, respectively. The increase in weight H. fossilis was the highest in T1 followed by T1 and T2, respectively. The initial weight (4.6±0.04 g) of fingerlings, stocked in all the ponds was same. The fish in treatment T1 showed the highest gain in weight (73.26±2.55 g) compared to the treatments T2 and T3, where stocking density of fingerlings was 74100/ha. However, the mean final weight of fingerlings in different treatments were significantly different (P
A cost-benefit analysis was performed to estimate the amount of profit that has been generated from these three types of culture operations. The results of the analysis are shown in T1, T2 and T3, respectively (Table 3). The cost of production in treatment T3 was consistently higher than those of treatments T1 and T2. Highest net benefit (in term of Bangladeshi Tk/ha and one US$ = Bangladeshi TK. 70.00) was obtained in treatment T1 (8,83,582.00) followed by T2 (5,50,072.00) and T3 (2,06,867.00) in that order. But it is remarkable that the second lowest net return levels were found to be in the treatment T2 and the lowest net return was recorded in treatment T3 and differed
significantly (P
Discussion
The environmental parameters exert an immense influence on the maintenance of a well aquatic environment and production of food organisms. Growth, feed efficacy and feed consumption of fish are normally governed by a few environmental factors (Brett, 1979). The primary productivity of water body is dependent on physico-chemical factors of water which are governed by environmental factors (Rahman et al. 1982). The temperature of the experimental ponds was within the acceptable range for fish culture that agrees well with the findings of Kohinoor et al. (1994). Transparency was consistently higher in T3, possibly due to the reduction of the plankton population by higher density of fish. The close variation in transparency might be due to application organic manure and grazing pressure of stocked fishes. (Boyd 1979). The pH values agree well with the findings of APHA 1998, Rahman and Rahman (2003) and Chakraborty et al. (2004). The dissolve Oxygen in the morning was low in ponds stocked with a high density of fish compared to ponds stocked with a low density. Similar results were observed by APHA 1998, Wahab et. al. (1994) and Rahman and Rahman (2003). Alkalinity levels indicate productivity of the ponds was medium to high (Bhuiyan. 1970). Higher total alkalinity values might be due to application of higher amount of lime doses during the experimental period (APHA 1998, Boyd 1982; Jhingran 1991).
In this experiment, supplementary feeds are more or less similar to the supplementary feeds supplied for the growth of H. fossilis under laboratory condition (Haque and Barua 1989). Growth in terms of weight, weight gain, RG and SGR of individuals of H. fossilis was significantly higher in T1 where the stocking density was low compared to the treatments of T2 and T3 although same food was supplied in all the treatments at an equal ratio. The low growth rate of H. fossilis in treatment T2 and T3 appeared to be related with higher densities and increased competition for food and space and an inverse relationship with in the stocking density provided that space-limiting effects operate on the population (Johnson 1965). In this experiment, at higher stocking densities, presence of abundant food substances could produce a comparative interaction among the population causing a stressful situation (Houde 1975).
During the experimental period, ecological factors, pond preparation, feed quality, healthy fish and stocking rate was influenced the high percentage of survival rate of H. fossilis (Choudhury et al. 1978). Highest survival rate was recorded in treatment T1 (Munshi 1996; Chakraborty et al., 2004, 2005). The FCR values of T1 are significantly higher than those T2 and T3, respectively. The FCR values are reported by Das and Ray (1989), Islam (2002) and Islam et al. (2002). De Silva and Davy (1992) stated that digestibility plays an important rule in lowering the FCR value by efficient utilization of food. Digestibility, in turn, depends on daily feeding rate, frequency of feeding, and type of food used (Chiu et al. 1987). However the lower FCR value in the present study indicates better food utilization efficiency, despite the values increased with increasing stocking densities. Significantly higher survival was noted in treatment T1, where, the stocking density was lower than T2 and T3. The reason for reduced survival rate in these treatments was due to higher stocking density of individuals as well as competition for food and space in the ponds (Tripathi et al. 1979; Haque et al. 1994; Kohinoor et al. 1994; Rahman and Rahman 2003 and Chakraborty et al 2006).
In this experiment, a significantly higher production (4288.19±5.67 kg/ha/yr3/4) were produced in treatment T1 where stocked with 74100 fingerlings.ha-1 of H. fossilis monoculture practice than those of from the treatment T2 and T3 stocked with 86450 and 98800 fingerlings.ha-1, respectively. Despite this, consistently higher net benefits (Tk.7,69,316.00/ha/yr3/4) were obtained from treatment T1 than those from the treatment T2 and T3 (Thakur and Das 1986; Kohinoor et al. 1993; Munshi 1996; Vijayakumar et al. 1998; Usmani et al. 2003; Chakraborty et al. 2005). Overall, highest growth, survival and benefits of H. fossilis monoculture practice were obtained from the treatment T1. In the present investigation, the amount of supplementary feeds given in different treatments was based on the number of fingerlings stocked and amount of feed provided per individual was kept at the same level. Hence, the observed low growth at higher stocking densities could be due to less availability of food and some variations in environmental parameters. The results in the present experiment are very similar to those of Munshi (1996); Kohinoor et al. (1998), Vijayakumar et al. (1998), Rahman and Rahman (2003), Usmani et al. (2003) and Chakraborty et al. (2005).
In conclusion, this study demonstrated that monoculture technology of treatment T1 is advisable for eight months culture of H. fossilis. Production technology of H. fossilis fish through application of present findings might be developed the aquaculture field of Bangladesh, meet up the protein deficiency of general people of Bangladesh and extremely helpful towards the protection of H. fossilis from extinction.
Acknowledgements
The authors wish to thank private hatchery owners Brahmaputra Fish Seed Hatchery who helps for successfully conducting the experiments with financial support.
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Hussain, M.G. and M.A. Mazid. 2001. Genetics Improvement and Conservation of Carp Species in Bangladesh. Bangladesh Fisheries Research Institute, Mymensingh, 56 p.
Islam, M.S. 2002. Evaluation of supplementary feeds for semi intensive pond culture of Mahaseer, Tor putitora (Hamilton). Aquaculture 212: 263-276.
Islam, M.S., S. Dewan, M.G. Hussain, M.A. Hossain and M.A. Mazid. 2002. Feed utilization and wastage in semi-intensive pond culture of mahseer, Tor putitora (Ham.). Bangladesh J. Fish. Res. 6: 1-9.
IUCN, Bangladesh 2000. Red book of threatened fish of Bangladesh. The world conservation Union Appendix 1, 61 p.
Jhingran, V.G. 1991. Fish and Fisheries of India, 3rd edn. Hindustan Publishing Corporation Delhi, India. 727 pp.
Johnson, W.E. 1965. On mechanism of self regulation of population abundance in Oncorhynchus nerka. Mitt. Int. Verein. Theor. Angew., 13: 66-87.
Kohinoor, A.H.M., M. Akhteruzzaman and M. S. Shah. 1993. Production of Puntius gonionotus (Bleeker) in ponds. Bangladesh J. Zool. 21(2): 77-83.
Kohinoor, A.H.M., M.Z. Haque, M. G. Hussain and M. V. Gupta. 1994. Growth and survival of Thi punti, Puntius gonionotus (Bleeker) spawn in nursery ponds at different stocking densities. J. Asia. Soc. Bangladesh Sci. 20(1): 65-72.
Kohinoor, A.H.M., M.L. Islam, M.A. Wahab, and S.H. Thilsted. 1998. Effect of mola (Amblypharyngodon mola, Hamilton) on the growth and production of carps in polyculture. Bangladesh J. Fish. 2(2): 119-126.
Munshi, J.S.D. 1996. Ecology of Heteropneustes fossilis, an air-breathing catfish of south-east Asia. Narendra Publishing House, Delhi. pp 174.
Rahman, M.A., H. Gheyasuddin, M.H. Rasid, and M.F.Z. Choudhury. 1982. Proximate composition and native quality of freshwater Zeol fishes of Bangladesh. Bangladesh J. Fish. 2-5(1-2): 37-43.
Rahman, M.R.and M.A. Rahman. 2003. Studies on the growth, survival and production of calbasu (Labeo calbasu, Ham.) at different stocking densities in primary nursing. Bull. Fac. Sci., Unv. Ryuyus, Jpn. 76: 245-255.
Saha, K.C. and B.C. Guha. 1939. Nutritional investigation on Bengal fish. Indian J. Med. Res. 26: 921-927.
Thakur, N.K.and P. Das. 1986. Synopsis of biological data on magur, Clarias batrachus. Bulletin No. 41. Ed Halder, D.D. CIFRI, Barrackpore.
Tripathi, S.D., A. Dutta, K.K. Sen Gupta and S. Pattra. 1979. High density rearing of rohu spawns in village ponds. In: Symposium of Inland Aquacult. (Abstracts) February 12-13, 1979. CIFRI. Barrack pore, 14 pp.
Usmani, N., A.K. Jafrim and M.A. Khan. 2003. Nutrient digestibility studies in Heteropneustes fossilis (Bloch), Clarias batrachus (Linnaeus) and Clarias gariepinus (Burchell). Aquaculture Research 34 (14): 1365-2109.
Vijayakumar, C., S. Sridhar and M.A. Haniffa. 1998. Low cost breeding and hatching techniques for the catfish Heteropnuestes fossilius for small-scale farmers. NAGA 21 (4): 15-17.
Wahab, M. A., Z. F. Ahmed, M. S. Haq and M. Begum. 1994. Compatibility of silver carp in the poly culture of cyprinid fishes. Prog. Agri. 5 (2): 221-227.
Zar, J.H. 1984. Biostatistics. Prentice-Hall, Inc. Englewood Cliffs, New Jersey, USA. 718 pp.
Table 1. Physico-chemical parameters of experimental ponds under three monoculture treatments
Parameters
Treatment
T1 T2 T3
Temperature (oC)24.88±7.22(14.20-32.80) 24.94±7.11
(14.30-33.05) 24.91±6.86 (14.25-32.85)
Transparency
(cm) 25.25±5.03c 30.08±5.88b38.08±6.81a
(19.44-34.12)(22.28-37.15)(29.15-46.66)
pH 8.15±1.18 8.05±1.16 8.01±1.44
(7.70-8.85) (7.75-8.88) (7.70-8.85)
Dissolved oxygen
(mg L-1)
4.77±1.02 4.88±1.14 4.52±1.32
(3.80-6.32)(3.85-6.11) (3.28-5.96)
Total alkalinity
(mg L-1)
151.22±7.15b 168.04±6.24a 145.55±6.25c
(142.55-185.40)(142.55-178.34)(130.45-165.08)
Figures with different superscripts in the same row varied significantly (P0.05). Values in the parenthesis indicate the range.
Table 2. Survival and production of Heteropneustes fossilis species as obtained under three treatments during eight months study.
Parameters Treatments
T1 T2 T3
No. of fish stocked ha-1
74100 98800 123500
Initial weight (g)
4.60±0.04 4.60±0.04 4.60±0.04
Final weight (g)
73.26±2.55a 53.72±4.14b 37.28±4.88c
No. of fish recovered ha-1
70307±22.05 85515±78.66 98686±96.55
Average daily gain (g)
0.29±0.0a 0.21±0.01b 0.14±0.01c
Relative growth (RG)
14.93±0.82 10.68±1.22 7.10±3.62
FCR 2.16±0.06a 2.39±0.06c 2.73±0.06e
SGR (% bw/day)
1.15±0.00a 1.02±0.01b 1.0±0.01c
Survival rate (%)
94.88 89.55 79.91
Total production
(kg.ha-1yr-3/4)
5150.70±5.67a 4593.90±34.55b 3676.0±85.44c
Total number of fingerlings harvested after 210 days
Relative growth (RG) = (mean final weight-mean initial weight)/ mean initial weight.
Average daily gain (g) = (mean final weight-mean initial weight)/time interval (days)
Specific growth rate (SGR) = (Ln mean final weight – Ln mean initial weight)/time interval (days) × 100
FCR (Food conversion ratio) = Total diet fed (kg)/ total wet weight gain (kg)
Table 3. Cost and return of fish production under a polyculture management of Heteropneustes fossilis during eight months study.
Item Amount TK•ha-1•m
Treatment
T1 (Tk) T2 (Tk) T4 (Tk)
Total return (TR)b
15,45,210a 12,40,353b 9,19,000c
a. Variable cost:
1. Price of fingerlings
1,48,200 1,97,600 2,47,000
2. Feed (Tk. 32.00 kg-1)
3,56,800 3,51,360 3,21,600 3. Organic fertilizer
4,000 4,000 4,000
4. Human labour cost
(Tk. 100/day)
42,000 42,000 42,000
5. Chemicals
6,580 6,850 7,075
6. Miscellaneous
10,000 10,000 10,000
Total Variable cost (TVC)
5,67,580 6,11,810 6,31,675
b. Fixed cost :
1.Pond rental value
17,290 17,290 17,290
2.Interest of operating capital
56,758 61,181 63,168
Total fixed cost (TFC)
74,048 78,471 80,458
Total cost
(TC= TVC+TFC)
6,61,628 6,90,281 7,12,133
Gross margin
(GM= TR-TVC)
9,77,630a 6,28,543b 2,87,325c
Net return (TR-TC)
8,83,582a 5,50,072b 2,06,867c
Values with different superscripts in the same row varied significantly (P
1 US$ =Tk. 70.00
Tk. 70.00 dec.-1 according to MAEP, Mymensingh (MAEP = Mymensingh Aquaculture Extension Project),10% interest according to BKB, Bangladesh
(BKB= Bangladesh Agricultural Bank)
Sale price of T1 Tk. 300/kg, T2 Tk. 270/kg and T3 Tk. 250/kg. Price related with size and weight
About the Author
Growth and Yield Performance of Endanger Singi, Heteropneustes fossilis (Bloch) under
Semi intensive Aquaculture
Chakraborty, B. K., Mirza J. A.
Fisheries Officer, Department of Fisheries, Bangladesh; Professor, Graduate training Institute, Bangladesh Agricultural University, Mymensingh, Bangladesh
Corresponding author: Chakraborty B. K.
Department of Fisheries
7, Umed Ali Road
Dhubakhola, Mymensingh-2200
Bangladesh
binay_borty@yahoo.com
Abstract
Production potential of Heteropneustes fossilis monoculture were assessed at a stocking density of 74,100, 98,800 and 1,23,500 ha-1 in the treatment T1, T2 and T3 for a period of 210 days at private Brahmaputra Fish Seed Farm, Puliamary, Shambhugonj, Mymensingh, Bangladesh. At stocking, all fingerlings were of same age with a mean weight of H. fossilis 4.6±0.04g, respectively. A commercial fish feeds, Saudi-Bangla were fed (32.21% crude protein) regularly. Fish production in treatment T1, T2 and T3 were 7276.08, 5135.16 and 4512.65 kg/ha/yr3/4, respectively. Food conversion ratio was significantly lower in T1 (2.16±0.06) than T2 and T3. RG was significantly higher in treatment T1 (14.93±0.82) than treatment T2 and T3. The mean differences of gross yield among different treatment were significant (P
The growth and production of fishes in term of gain in weight under three treatments were investigated and monitored fortnightly. The results obtained are presented in table 2, which
Table 1. Physico-chemical parameters of experimental ponds under three monoculture treatments
Parameters
Treatment
T1 T2 T3
Temperature (oC) 24.88±7.22
(14.20-32.80) 24.94±7.11
(14.30-33.05) 24.91±6.86
(14.25-32.85)
Transparency
(cm) 25.25±5.03c
(19.44-34.12) 30.08±5.88b
(22.28-37.15) 38.08±6.81a
(29.15-46.66)
pH
8.15±1.18
(7.70-8.85) 8.05±1.16
(7.75-8.88) 8.01±1.44
(7.70-8.85)
Dissolved oxygen
(mg L-1) 4.77±1.02
(3.80-6.32) 4.88±1.14
(3.85-6.11) 4.52±1.32
(3.28-5.96)
Total alkalinity
(mg L-1) 151.22±7.15b
(142.55-185.40) 168.04±6.24a
(142.55-178.34) 145.55±6.25c
(130.45-165.08)
Figures with different superscripts in the same row varied significantly (P0.05). Values in the parenthesis indicate the range.
Total number of fingerlings harvested after yr-3/4
Relative growth (RG) = (mean final weight-mean initial weight)/ mean initial weight.
Average daily gain (g) = (mean final weight-mean initial weight)/time interval (days)
Specific growth rate (SGR) = (Ln mean final weight – Ln mean initial weight)/time interval (days) × 100
FCR (Food conversion ratio) = Total diet fed (kg)/ total wet weight gain (kg)
(4.6±0.04 g) of fingerlings, stocked in all the ponds was same. The fish in treatment T1 showed the highest gain in weight (73.26±2.55 g) compared to the treatments T2 and T3, where stocking density of fingerlings was 74100/ha. However, the mean final weight of fingerlings in different treatments
Figure 1. Fortnightly mean weight (g) gain of Singi, Heteropneustes fossilis under three treatments during eight months study.
were significantly different (P
lowest production was recorded and differed significantly (P
A cost-benefit analysis was performed to estimate the amount of profit that has been generated from these three types of culture operations. The results of the analysis are shown in T1, T2 and T3, respectively (Table 3). The cost of production in treatment T3 was consistently higher than those of treatments T1 and T2. Highest net benefit (in term of Bangladeshi Tk/ha and one US$ = Bangladeshi TK. 70.00) was obtained in treatment T1 (8,83,582.00) followed by T2 (5,50,072.00)
Table 3. Cost and return of fish production under a polyculture management of Heteropneustes fossilis during eight months study.
Item Amount TK•ha-1•month-8 Remarks
Treat. T1 (Tk)Treat.T2(Tk) Treat.T4 (Tk)
Total return (TR)b
15,45,210a 12,40,353b 9,19,000c
Price related with size and weight
a. Variable cost:
1. Price of fingerlings
1,48,200 1,97,600 2,47,000
2. Feed (Tk. 32.00 kg-1)
3,56,800 3,51,360 3,21,600
3. Organic fertilizer
4,000 4,000 4,000
4. Human labour cost
(Tk. 100.00 day-1)
42,000 42,000 42,000
5. Chemicals
6,580 6,850 7,075
6. Miscellaneous
10,000 10,000 10,000
Total Variable cost (TVC)
5,67,580 6,11,810 6,31,675
b. Fixed cost :
1.Pond rental value
17,290 17,290 17,290 Tk. 70.00 dec.-1 according to MAEP, Mymensingh
2.Interest of operating capital 56,758 61,181 63,168 10% interest according to BKB, Bangladesh
Total fixed cost (TFC)
74,048 78,471 80,458
Total cost
(TC= TVC+TFC)
6,61,628 6,90,281 7,12,133
Gross margin
(GM= TR-TVC)9,77,630a 6,28,543b 2,87,325c
Net return (TR-TC)
8,83,582a 5,50,072b 2,06,867c
Values with different superscripts in the same row varied significantly (P
a1 US$ =Tk. 70.00
MAEP = Mymensingh Aquaculture Extension Project, BKB= Bangladesh Krishi (Agricultural) Bank
Sale price of T1 Tk. 300.00 kg-1, T2 Tk. 270.00 kg-1 and T3 Tk. 250.00 kg-1.
and T3 (2,06,867.00) in that order. But it is remarkable that the second lowest net return levels were
found to be in the treatment T2 and the lowest net return was recorded in treatment T3 and differed
significantly (P
Discussion
The environmental parameters exert an immense influence on the maintenance of a well aquatic environment and production of food organisms. Growth, feed efficacy and feed consumption of fish are normally governed by a few environmental factors (Brett, 1979). The primary productivity of water body is dependent on physico-chemical factors of water which are governed by environmental factors (Rahman et al. 1982). The temperature of the experimental ponds was within the acceptable range for fish culture that agrees well with the findings of Kohinoor et al. (1994). Transparency was consistently higher in T3, possibly due to the reduction of the plankton population by higher density of fish. The close variation in transparency might be due to application organic manure and grazing pressure of stocked fishes. (Boyd 1979). The pH values agree well with the findings of APHA 1998, Rahman and Rahman (2003) and Chakraborty et al. (2004). The dissolve Oxygen in the morning was low in ponds stocked with a high density of fish compared to ponds stocked with a low density. Similar results were observed by APHA 1998, Wahab et. al. (1994) and Rahman and Rahman (2003). Alkalinity levels indicate productivity of the ponds was medium to high (Bhuiyan. 1970). Higher total alkalinity values might be due to application of higher amount of lime doses during the experimental period (APHA 1998, Boyd 1982; Jhingran 1991).
In this experiment, supplementary feeds are more or less similar to the supplementary feeds supplied for the growth of H. fossilis under laboratory condition (Haque and Barua 1989). Growth in terms of weight, weight gain, RG and SGR of individuals of H. fossilis was significantly higher in T1 where the stocking density was low compared to the treatments of T2 and T3 although same food was supplied in all the treatments at an equal ratio. The low growth rate of H. fossilis in treatment T2 and T3 appeared to be related with higher densities and increased competition for food and space and an inverse relationship with in the stocking density provided that space-limiting effects operate on the population (Johnson 1965). In this experiment, at higher stocking densities, presence of abundant food substances could produce a comparative interaction among the population causing a stressful situation (Houde 1975).
During the experimental period, ecological factors, pond preparation, feed quality, healthy fish and stocking rate was influenced the high percentage of survival rate of H. fossilis (Choudhury et al. 1978). Highest survival rate was recorded in treatment T1 (Munshi 1996; Chakraborty et al., 2004, 2005). The FCR values of T1 are significantly higher than those T2 and T3, respectively. The FCR values are reported by Das and Ray (1989), Islam (2002) and Islam et al. (2002). De Silva and Davy (1992) stated that digestibility plays an important rule in lowering the FCR value by efficient utilization of food. Digestibility, in turn, depends on daily feeding rate, frequency of feeding, and type of food used (Chiu et al. 1987). However the lower FCR value in the present study indicates better food utilization efficiency, despite the values increased with increasing stocking densities. Significantly higher survival was noted in treatment T1, where, the stocking density was lower than T2 and T3. The reason for reduced survival rate in these treatments was due to higher stocking density of individuals as well as competition for food and space in the ponds (Tripathi et al. 1979; Haque et al. 1994; Kohinoor et al. 1994; Rahman and Rahman 2003 and Chakraborty et al 2006).
In this experiment, a significantly higher production (4288.19±5.67 kg/ha/yr3/4) were produced in treatment T1 where stocked with 74100 fingerlings.ha-1 of H. fossilis monoculture practice than those of from the treatment T2 and T3 stocked with 86450 and 98800 fingerlings.ha-1, respectively. Despite this, consistently higher net benefits (Tk.7,69,316.00/ha/yr3/4) were obtained from treatment T1 than those from the treatment T2 and T3 (Thakur and Das 1986; Kohinoor et al. 1993; Munshi 1996; Vijayakumar et al. 1998; Usmani et al. 2003; Chakraborty et al. 2005). Overall, highest growth, survival and benefits of H. fossilis monoculture practice were obtained from the treatment T1. In the present investigation, the amount of supplementary feeds given in different treatments was based on the number of fingerlings stocked and amount of feed provided per individual was kept at the same level. Hence, the observed low growth at higher stocking densities could be due to less availability of food and some variations in environmental parameters. The results in the present experiment are very similar to those of Munshi (1996); Kohinoor et al. (1998), Vijayakumar et al. (1998), Rahman and Rahman (2003), Usmani et al. (2003) and Chakraborty et al. (2005).
In conclusion, this study demonstrated that monoculture technology of treatment T1 is advisable for eight months culture of H. fossilis. Production technology of H. fossilis fish through application of present findings might be developed the aquaculture field of Bangladesh, meet up the protein deficiency of general people of Bangladesh and extremely helpful towards the protection of H. fossilis from extinction.
Acknowledgements
The authors wish to thank private hatchery owners Brahmaputra Fish Seed Hatchery who helps for successfully conducting the experiments with financial support.
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Vijayakumar, C., S. Sridhar and M.A. Haniffa. 1998. Low cost breeding and hatching techniques for the catfish Heteropnuestes fossilius for small-scale farmers. NAGA 21 (4): 15-17.
Wahab, M. A., Z. F. Ahmed, M. S. Haq and M. Begum. 1994. Compatibility of silver carp in the poly culture of cyprinid fishes. Prog. Agri. 5 (2): 221-227.
Zar, J.H. 1984. Biostatistics. Prentice-Hall, Inc. Englewood Cliffs, New Jersey, USA. 718 pp.
Space shuttle Atlantis close to 120 million miles
CAPE CANAVERAL, Fla. – Space shuttle Atlantis closed in on the 120 million-mile (193-million-kilometre) mark as its final voyage neared an end and astronauts inspected their ship in advance of Wednesday’s landing.
