COMPARATIVE STUDY ON GROWTH PERFORMANCE OF THAI SHARPUNTI ( Puntius gonionotus ) USING TWO DIFFERENT WEEDS DUCK WEED ( Lemna minor ) AND AZOLLA FERN ( Azolla pinneta )

Thai Sharpunti Duck weed Azolla fern Growth performances The comparative growth performance study of Thai Sharpunti (Puntius gonionotus) was conducted from 20th March to 18th May, 2012by using duck weed (Lemna minor) and Azolla fern (Azolla pinneta) as in earthen pondof the Department of Aquaculture, Bangladesh Agricultural University, Mymensingh. Duck weed and Azolla fern were supplied as dietary feed in two separate treatments and each with three replications. Fifteen fingerlings of Thai sharputi was stocked in each pond. Average size and weight of Thai sarputi were 5.75 cm and 21g in T1 and 5.50 cm and20g in T2, respectively. The ranges of physico-chemical parameters viz, water temperature (25.00 to 33.50C), air temperature (31.00 to 34.50C), transparency (28 to 34 cm),dissolved oxygen (6.00 to 7.20 mg/l), free CO2 (2.00 to 3.33 mg/l), pH (6.9 to 7.45), total alkalinity (48 to 61 mg/l), phosphate-phosphorus (1.40 to 2.50 mg/l) and nitrate-nitrogen (2.13 to 3.20 mg/l) were within the productive range. Initial body weight, final body weight, weight gain, survival rate, specific growth rate(SGR), food convertion ratio (FCR), percent weight gain, average daily gain (ADG) were observed as21 and 20g, 356g and 308g, 335 and 288g, 90 and 85%, 558and 480% per day, 5.28 and 6.10, 1595 and 1440%, 5.58 and 4.80g in both the treatments,respectively. Calculated gross and net fish production in T1 with duck weed were 2.40 and 2.08 ton/ha/yr and in T2 with Azolla fern were 2.26 and 1.94 ton/ha/yr, respectively. It was found that the net fish production in T1 was 1.32 times higher than T2 (P≤0.01, 0.05). The present study showed influence of duck weed as dietary feed on the production of Thai Sharpunti (P. gonionotus) was positively significant. So it might be concluded that duckweed had better effect as dietary feed than Azolla fern on monoculture of Thai sharpunti.


INTRODUCTION
Fisheries sector has been playing a significant role in nutrition, employment, foreign exchange earnings, food supply and more importantly socioeconomic stability in the rural areas.In 2009-2010 total fish production of Bangladesh was 28.99 lakh metric tons but that is not enough for our growing population.Therefore, immediate attention must be given to maximize the fish production by minimizing the production cost for everincreasing population as well as to build up the national economy.In Bangladesh more or less every rural homestead has a back yard pond which retains water for about 9-12 months.There are 2.86 million ponds in Bangladesh covering an area of 28,834 ha (Rahman and Hussain, 2000).The average fish production in traditionally managed ponds in Bangladesh was estimated to be 870.0kg/ha/yearwhich is very low and that can be increased by many fold through improved culture and management practices.Considering the aquaculture potential of Puntius gonionotus, it was introduced to Bangladesh from Thailand in 1977.It grows fast, reaches marketable size within four months and is ideal for seasonal pond and road side ditches.In perennial water bodies, polyculture or mono culture of this sharpunti has economically viable and technically sustainable.Silver barb feeds on macrophytes including duck weed (Lemna spp.) and Azolla fern (Azolla spp.) and sharpunti is an appropriate species for culturing seasonal ponds and rice fields in monoculture.Noor et al. (2000) evaluated the suitability of duckweed as dietary fish meal substitute for silver barb and found that 10% of the dietary fish meal protein could be replaced by duckweed in the diet.Azim and Wahab (2003) found that duckweed has significant positive effect on growth rates of exotic Thai silver barb, common carp and indigenous catla fish.Silver barb respond well to comparatively low cost simple management practices (Akhtaruzzaman, 1991).Duck weed and Azolla holds a great potential as a cheap source of fish food.Many works already done on duck weed used as fish, but there is no work have so far been under taken about the comparative growth performance of Thai sharpunti feeding on duck weed and water fern.The present studies on the ingestion rate and growth performance of Puntius gonionotus were under taken to evaluate the conversion efficiency of duck weed and Azolla fern by Thai sharpunti and to study the comparative proximate composition energy distribution of duck weed and Azolla fern.

MATERIALS AND METHODS
A series of six ponds of Department of Aquaculture, Bangladesh Agricultural University, Mymensingh, were selected to conduct the research work from 20 th March to 18 th May, 2012.The ponds are rectangular in shape.The size, depth, basin conformation of all the six ponds are more or less similar.The ponds are free from aquatic vegetation and well-exposed to sunlight.The surface area of each of the ponds is about 26 m 2 with an average water depth of 1.0meter.The ponds were completely dependent on water supply from a deep tube-well.The pond's wall is well protected and covered with fine net.Fifteen fingerlings of Thai sharpunti (P.gonionotus) were stocked in each the pond.The average length and weight of sharpunti were 5.50 cm, and 21 g.After collection the fresh weeds were weighed and then supplied to the fish culture ponds under treatment-1 and treatment-2 at the rate of 60% of total body weight of all the fish of the ponds.The physical parameters such as temperature ( °C) and transparency (cm) and chemical water quality parameters such as dissolved oxygen (mg/l), pH, free carbondioxide (mg/l), total alkalinity (mg/l), phosphate phosphorus (PO4-P) (mg/l), nitrate nitrogen (NO3-N) (mg/l) were done by water quality parameters test kits.

Statistical analysis
F-test of growth performance of Thai Sharpunti (P.gonionotus) in treatment-1 and treatment -2 was done by a computer using SPSS package programme.

Physical and chemical parameters
The results of the physical and chemical parameters recorded during the experimental period presented in the Table 1 and Table 2 In the present study, range of water temperature was within suitable range for fish culture (29.25 to 33.50 °C).Wahab et al. (1994) found transparency ranging from 15-55 cm in polyculture pond.Kohinoor (2000) recorded transparency ranging from 15 to 58 cm.In the present experiment, the transparency values in treatment-1 and treatment-2 were closely near to productive range (28 to 34 cm).Aminul (1996) stated that the water temperature ranged from 25 to 35 °C was suitable for culture of fish.Kohinoor (2000) measured dissolved oxygen 2 to 7.4 mg/L in the research ponds of Bangladesh Agricultural University campus, Mymensingh.From the above findings, it was concluded that the oxygen content of the present experimental ponds were within the good productive range.During the study period the fluctuations of free carbondioxide in treatment-1 and treatment-2 range from 2.30 to 3.33 mg/L.The mean values of free carbondioxide were 2.81 ±0.35 mg/L in T1 and 2.93 ± 0.28 mg L in T2.Israfil (2000) and Kabir (2003) observed more or less similar results.Fluctuations of the pH values of the experimental treatments ranged from 6.90 to 7.45.The mean values of pH were 7.12 ± 0.23 in T1 and 7.08 ± 0.13 in T2.Dewan et al. (1991) stated that the optimum pH range for carp polyculture in pond is 6.5 to 9.0.Israfil (2000) and Kabir (2003) found almost similar results.According to Rahman (1992) total alkalinity of productive ponds should be 20 ppm or more.Total alkalinity in the experimental treatments ranged from 48.00 to 61.33 mg/L.The mean values of total alkalinity were 50.58 ± 1.98 mg/L in T1 and 50.16 ± 2.67 mg/L T2.The variations of phosphate-phosphorusranged from 1.40 to 2.50 mg/L.The mean values of PO4-P were 1.89 ± 0.37 mg/L in T1 and 1.98 ± 0.32 mg/L T2.Wahabet al. (1995) found the concentrations of phosphatephosphorus from0.09to5.20 mg/Lexperimental ponds at Bangladesh Agricultural University, Mymensingh.From the present findings, it might be concluded that phosphate-phosphorus content, were within the productive range.Variations of nitrate-nitrogen of ranged from 2.13 to 3.20 mg/L during the study period.The mean values of nitrate-nitrogen were 2.75 ± 0.39 mg/L in T1 and 2.79 ± 0.33 mg/L in T2.From the above discussion, it may be concluded that all the parameters of experimental ponds were suitable for fish culture.

Growth Performances of Thai Sharpunti (Puntius gonionotus)
The final weight was 356g in T1 and 308g in T2.The final weight in T1 was significantly higher than T2 (P ≤0.01).The live weight gain was 335g in T1 and 288g in T2.The live weight gain in T1 was significantly higher than T2 (P ≤0.01).The percent weight gain was 1595% in T1 and 1440% in T2.The percent weight gain in T1 was significantly higher than T2 (P ≤0.05).The average daily weight gain was 5.58g in T1 and 4.80g in T2.The average daily weight gain in T1 was significantly higher than T2 (P ≤0.01).The specific growth rate was 558% in T1 and 480% in T2.The specific growth rate in T1 was significantly higher than T2 (P ≤0.01).The food conversion ratio was 5.28 in T1 and 6.10 in T2.The food conversion ratio (FCR) in T1 was significantly lower than T2 (P ≤0.01).The gross production was 2.40 ton/ha/yr in T1 and 2.08 ton/ha/yr in T2.The gross production in T1 was significantly higher than T2 (P ≤0.01).The net production was 2.26ton/ha/yr in T1 and 1.94 ton/ha/yrin T2.The net production in T1 was significantly higher than T2 (P ≤0.01).Talukder et al. (2004) found SGR of fish (P.gonionotus) from 2.42to 2.03% in treatment-1 and treatment-2 respectively where duck weed were used as supplemental feed at a rate of 40% body weight.Talukder et al. (2004) found 2.76 ton/ha/yr net production of sharpunti where fresh duck weed was supplemental feed and the production was significantly higher in ponds with supply of duck weed than without supply of duck weed.Kohinoor et al. (1999) observed the effectiveness of duck weed as low cost supplementary feed through 6 months production trial of Thai sharpunti.Abdel-Fattah and Abdel-Aziz (1990) used Azolla pinnata as protein source for tilapia (Oreochromis niloticus) fingerlings.FCR value in T1 was significantly lower than T2.The reason behind the higher production in T1 was due to the supply of duck weed as dietary feed which had higher nutritive value of protein content then Azolla fern in T2.
F-test of gross and net productions showed(P ≤ 0.01,0.05)significantly higher production in T1 than T2 i.e. influence of duck weed as dietary feed on the production of Thai Sharpunti (P.gonionotus) was positively significant.So it might be concluded that duckweed had better effect as dietary feed than Azolla fern on monoculture of Thai sharpunti.

CONCLUSION
The present study showed higher growth performance in treatment-1 followed by treatment-2.The net fish production was 1.32 times higher than T2.FCR value in T1 was significantly lower than T2.F-test of gross and net productions showed (P ≤ 0.01, 0.05) significantly higher production in T1 than T2 i.e. influence of duck weed as dietary feed on the production of Thai Sharpunti (P.gonionotus) was positively significant.So it might be concluded that duckweed had better effect as dietary feed than Azolla fern on monoculture of Thai sharpunti.
Consumtion) = The gross energy content of the food ingested.P (Production) = Energy utilized in growth materials.R (Respiration) = Net loss of energy as heat.U (Urinary loss) = Energy loss in nitrogenous excretory product.F (Fecal loss) = Energy loss in the feces.

Table 1 .
. Fluctuations of physical parameters in treatment-1 and treatment-2 during the experimental period

Table 2 .
Fluctuations of chemical parameters in treatment-1 and treatment-2 during the experimental period

Table 3 .
Proximate Composition of 100g supplied Duckweed and Azolla fern