EFFECTS OF DIFFERENT PROTEIN LEVEL FEEDS ON THE FINGERLINGS PRODUCTION OF RIVERINE ENDANGERED Notopterus chitala (Hamilton, 1882) IN PONDS

Received 14 November, 2020 Revised 17 December, 2020 Accepted 27 December, 2020 Online 12 January, 2021 --------------------------------


INTRODUCTION
Notopterus chitala is widely distributed in deep and clear waters in the rivers, beels, reservoirs, haors, baors and ponds in Bangladesh (Islam and Hossain, 1983, Hafizuddin 1985, Azadi et al., 1994. It is rich in nutritive value (Jafri et al., 1994) and high valued species in Bangladesh. In recent years, the catch of this species has been declining fast due to environmental degradation (Hossain et al., 2006). However, over exploitation, pollution and related man-made intervention on their natural habitats, have considerably reduced the population of this species and listed as endangered (IUCN, 2015). Chitala is one of the most important species that has been prioritized as a new candidate species (Ayyappan et al., 2001) for aquaculture. Actually, the success of commercial aquaculture operations depends on the availability of suitable diets that are efficiently digested and provide the required nutrients for optimum growth (Mokolensang et al., 2003). It is important to develop suitable fry rearing system with optimum protein containing feed for domestication and conservation of this species. Successful aquaculture operation of these high value species mostly depends on the application of nutrient rich feed (Dey et al., 2008). Fish feed generally constitutes 60-70% of the operational cost in intensive and semi-intensive aquaculture system (Singh and Balange.2005). An important approach to reduce feed costs in commercial aquaculture is to develop proper feed management and husbandry strategies (Lovell et al., 1998). Protein is the most expensive nutrient in fish diet (Pillay, 1990). Increasing protein levels in feeds can lead to improved fish production, but excessive dietary protein is not economical for fish culture (Erondu et al., 2006;Sheunn et al., 2003). Though this species has been reported quite favorable in pond habitat, but their monoculture technique with different protein-based feed has not yet been developed. Therefore, the present study was designed to evaluate the production performance of Notopterus chitala in monoculture management using different protein-based feed in northern area of Bangladesh.

Study area and experiment pond
The experiment was conducted in the nine experimental nursery ponds situated on the north side of the department of Fisheries, University of Rajshahi for a period of 60 days. The average area of the ponds was 0.8 decimal (0.0032 hector). The water depth was maintained around 1.0-1.25 m by using pump machine at regular intervals. Prior to the experiment, the ponds were dried, aquatic vegetation and all fishes and other predatory species were completely removed. Lime (Calcium carbonate) was applied at the rate of 247 kg/ha. Three different diets for chital fry were tested in this experiment. Each diet of chital fry was considered as treatment and replicated thrice. The treatment assignment was as T1(35 % protein), T2(30% protein), T3 (25% protein). The fry stocking rate per hectare was 7410 (30/deci)

Stocking and feed management of fry
The fry of Chital (Notopterous chitala) were collected from Padma River. Fry were transported to the experimental site through plastic bag with proper aeration. The chital fry (wt.5.6±0.19 g) was randomly stocked at the rate of 7410 per hector for each treatment. The stocked fries were fed with pellet diet containing different level of protein for different treatments (For T1 -35%, T2-30%, and T3-25%). Six ingredients were used in the formulated feed at different percentages and the ingredients were calculated for their inclusion rate and the results are shown in table-1&2. The proximate composition of feed ingredients was analyzed according to the methods given in Association of Official Analytical Chemists (AOAC, 1990). Experimental diets were formulated according to the Pearson square method. Feed requirement were calculated and adjusted after sampling of fish once in a fortnight. The feeds were initially fed at the rate of 10% of body weight for thirty days and the rate was reduced to 8% gradually next 30 days.   Growth sampling of fish Fish were sampled fortnightly using cast net to assess their growth and health condition. At least 10% fish from each pond was taken to make assessment of growth trends and to readjust feeding rate. Length and weight of sampled fish were measured using a measuring scale and digital electric balance (OHAUS, MODEL No. CT-1200-S). Fishes was handled carefully to avoid stress during sampling.

Water quality monitoring
The different water quality parameters such as temperature (ºC), transparency (cm), pH, dissolved oxygen (mg/l), alkalinity, ammonia-nitrogen (mg/l) of the ponds were monitored between 8:30-9:30 A.M. in each fortnight to record the physic-chemical condition of the pond. A centigrade thermometer within the range of 0°C to 120°C was used to record the water temperature. A secchi disk (20 cm diameter) was used for the measurement of water transparency. pH of pond water was measured by the help of a pH meter (Hanna, Italy) at the pond site. The dissolved oxygen, total alkalinity and ammonia-nitrogen concentration of water was determined by the Winkler's titration method (APHA, 1992) and expressed in milligram per liter (mg/1) of water.

Growth parameters
Growth and feed utilization parameters (Mean weight gain, Average daily gain, Specific growth rate, Survival rate, Food conversion ratio) were used to evaluate the growth performance of fishes under different treatments. Data on growth collected from different treatments during the trials were calculated and analyzed using standard methods. : Ricker,1975, De Silva, 1989, Castell and Tiews,1980.

Profit and statistical analysis
Data on both fixed and variable costs were recorded to determine the total cost (BDT/ha/60 days). Total return determined from the market price of fish was expressed as BDT/ha/60 days. For the analysis of collected data, one-way analysis of variance (ANOVA) was performed using the SPSS (Statistical Package for Social Science, evaluation version-16.0) program and significance was assigned at the 0.05% level and tested Duncan's New Multiple Range Test (DMRT) to identify significant differences among the mean values. (Zar, 1984).

Water quality parameters
Mean value of water quality parameters over the 60 days rearing of Notopterus chitala are presented in table 3. Physico-chemical and biological environment of a water body are mostly influenced by water temperature which is the most important physical factors. In present study, temperature varied from 26.70 to 33.60°C with the means of 30.67 ± 0.57 ºC, 29.73± 0.63, 30.75 ± 0.60 °C in treatments-1, 2 and 3, respectively. Samad et al. (2005) found water temperature varied from 29.00°C to 30.6 °C in nursery pond that was almost similar to those obtained in the present study. Rahman et al. (1992) stated water temperature ranged were 25.5°C to 30.0°C, which was favorable for fish culture Water transparency is a gross measure of pond productivity. It acts as an index of productivity of a water body. It is closely related to the phytoplankton abundance. Wahab et al. (1995) suggested that the transparency of productive water should be 40 cm or less. Comparatively higher mean value (36.56 ± 0.44cm) of water transparency was found with the treatment T3 and lower mean value (33.72 ± 0.21cm) was found with the treatment T1. This might be due to the frequent application of feed and seasonal variation in plankton concentration. This finding strongly agreed with Boyd (1998)   In the present study, dissolved oxygen varied from 5.29 ± 0.04mg/1to 5.46 ± 0.03 mg/1 (Table-2). The highest value was found with treatment T3 whereas the minimum value of dissolved oxygen was found with treatment T1. pH is considered as an important factor in aquaculture and treated as the productivity index of a waterbody. The pH value of the experimental pond varied from 7.53 ± 0.02 to 7.59 ± 0.02 which were within more or less acceptable range of 6.5-9.0 (Boyd, 1990). During the experimental period pH of the experimental pond was slightly alkaline, which indicated a good pH condition for fish culture. Similar findings were found by Saha et al. (2003) and Samad et al. (2004).
In alkaline waters essential nutrients are found in higher quantities and this is the most important reason for higher biological productivity in alkaline waters than in acidic waters. But highly alkaline condition is not favorable for biological production (Rahman, 1992). Total alkalinity values obtained during the study period were found to vary from 140.75 ± 1.65 mg/1 to 143.06 ± 2.02mg/1. Total alkalinity in the present study agreed with the findings of Samad et al. The presence of ammonia in pond is normal due to natural fish metabolism and microbiological decay of organic matter. Chan et al (2007) found that lower than 1mg/l of NH3 gas content in pond was good for fish culture. The value of NH3-N was found to be ranged from 0.105 ± 0.005 mg/1 to 0.113 ± 004 mg/1. Ali et al.  New (1987) reported that excessive use of feed or fertilizer caused sediments in the pond bottom which may produce ammonia and other gases. However, ammonia-nitrogen level in the rearing ponds was not toxic to cultured fishes.

Growth performance of Notopterus chitala
Growth parameters such as final weight, gain in weight and SGR% showed (Table-4) statistically significant differences (P<0.05) among three treatment groups. The effect of feed on the production of fingerling was significantly different (Hossain et al., 2007). Dietary protein is used by fish for growth, energy and body maintenance (Kaushik and Medale, 1994). N. chitala was found to be fast-growing and reached 2 kg in 243 days (Rahmatullah et al., 2009). The highest final weight (19.31 ± 0.23 g) was found with the treatment T1 (about 35% proteins) and the lowest final weight (13.96±0.15 g) was examined with the treatment T3 (about 25% proteins). The growth in length was found to be very high in comparison with weight. It might be due to laterally flattened body of N. chitala which gain less weight with increase of body length (Azadi et. al., 1994). Degain et al. (1989) established direct relationship between growth rate and protein content of diet. In the present studies also significantly higher growth rate was recorded in high protein (35%) diets than the low protein (25%) diets. Renukaradya and Varghese (1986) also concluded that daily growth rate of Catla catla was higher with diets having 30 and 40% protein which is similar to the present study. Samad et al (2005) obtained similar trends of growth rate of Clarias batrachus fingerlings in earthen ponds of Bangladesh.

Specific growth rate and average daily gain
The Specific growth rate (SGR, % bwd -1 ), The average daily gain (ADG, %) was also found higher in the treatment T1 (0.18±0.005) whereas, the lowest value was found in T2 (0.14±0.005) and T3 (0.11±0.005). All values were significantly (P<0.05) different among the treatments. Samad et al. (2005) found the best ADG, (0.138g) in the experiment of C batrachus. Sangrattanakhul (1989) found the ADG of A. testudineus fish ranging from 0.100 to 0.120 g and this finding was lower than the findings of present study due feed and variation of species.Panase and Mengumphan (2015) also found the same trend as like in the present experiment. The present study showed that significant reduction in ADG resulted for reducing protein level in feeds.

Survival rate
The survival rate (%) during the study period were 96.66 ± 0.96 %, 93.33±0.96 and 88.89 ± 2.00 % in the T1, T2 and T3 respectively, which were significant different (P>0.05) among the treatments (Table-3). This survival rate is agreed with the survival rate of 88.00 to 94.00 %, recorded by Sarkar et al. (2006) in intensive recirculatory tank culture system of Chitala chitala (Hamilton). Rahmatullah et al. (2009) found survival rate for chital (N. chitala) was 47% which is too much lower than the present study due to the longer culture period with tilapia as a cospecies. Hossain et al. (2006) reported that, the highest survival rates of N. chitala fry (98.50%) was observed when fish spawn was used as feed for N. chitala. Samad e t al. (2016) also obtained that the survival rate of Notopterus chitala fry was significantly varied from 82.33±1.20% to 94.50±1.50% which is similar trend to the survival rate with the present study. The survival rate achieved in the present experiments were indicating that the healthy and suitable ecological nature of the ponds.

Food conversion ratio (FCR)
The food conversion ratio (FCR) values were found lowest in T1 (3.02±0.09) followed by T2 (3.68±0.07) and T3 (4.51±0.20), which were significantly different among the treatments. The experiment showed that T1 gave excellent results where the fish's feeds on high protein (35%) containing feed. Samad et al. (2014) recorded comparatively lower FCR value by using 30% proteins containing feeds for Clarias batrachus. The FCR value in T3 was much higher than the findings of Haque and Mazid (2005). The improved FCR has important cost saving implication. This finding was concurred with those of Siddiky et al. (2015) in which the FCR value ranged from 1.50 to 2.00 for Mystus gulio and Paul et al. (2012) for Ompok pabda the FCR was of 2.17 at 33% protein level. Samad et al. (2004) also obtained the best FCR value for fry rearing of H fossilis was 3.25. Finally, all the above citation approved about the feed efficiency and better feed utilization in the culture unit.

Production and cost-benefit analysis of N. chitala
The maximum fish production (138.32±1638 kg/ha) was obtained in T1 under the 35% protein contains feed was used (Table-4). The lowest fish production (89.65±966 kg/ha) was observed in T3 which might be due to the lower protein level (25% protein) feed used. The annual yields of chital (N. chitala) were 0.92 t ha- 1 year -1 (Rahmatullah et al., 2009). The present result is lower might be due to 60 days culture period and use of different diet in fry rearing. In another study, Samad et al (2016) obtained the highest production (300.78±1.62 kg ha-1 ) under different stocking density for N. chitala fry culture in earthen ponds for a period of 75 days. This was probably due to the effect of feed with different inclusion level and variation of the culture period. The cost of different inputs and economic return from the sale of fishes in are summarized in table 5. Among the treatments, the highest production and total income 250690±324.81 BDT/ha/60 days were found in T1 and consequently provides the highest net profit 138690±175.36 BDT/kg/60 days in T1, where fishes were fed 35% protein containing feed. Similarly, the net profit in treatment T2 (113530±59.89 BDT/ha/60 days) and lowest in T3 (100430±298.75 BDT/ha/60 days) which is statistically significant difference (P>0.05) among the treatment. Samad et.al., (2014) analyzed the maximum net profit of walking catfish (Clarias batrachus) culture was 713542 BDT/ha/120 days which is more than the net profit of the present study because of longer culture period with different diets.
The Cost benefit ratio (CBR) of N. chitala in different treatments of the present study was fairly high ranging from 1:1.23 (T1) to 1:0.95 (T3) and statistically significant different among the treatments. Samad et. al., (2014) recorded that the CBR of Clarias batrachus culture was higher (1:1.24) when 30% protein containing feed used. In recent study, Samad et al. (2016) found best C.B.R (1:1.80) in the experiment of nursery rearing of N. Chitala and this finding was higher to the present outcome. The cause might be due to feed management, variation of study period and stocking size of the species. Considering overall production and economic analysis of the present study the best production obtained in treatment T1 with 35% protein containing feed. Therefore, in N. Chitala farming using indigenous high protein containing feeds is suggested for commercial farmer in Bangladesh.

CONCLUSION
In the present study, feed which contains 35% protein was found the best among the treatments. Thus, the study indicated that feed has direct effects on the growth and production of N. chitala fingerlings under pond condition. A feed that contains more protein is best suited that the farmer can maximize their benefit by culturing N. chitala providing high protein feeds instead of commonly used low protein feeds. Therefore, further studies can be carried out with increasing protein level in feed to see the effect of the fingerling production of Notopterus chitala for longer period of time to evolve a definite pond culture technology of N. chitala in Bangladesh.