COUNTERGRADIENT VARIATION IN GROWTH OF BARB ( Barbonymus balleroides Val . 1842 ) DOMESTICATED AT DIFFERENT ALTITUDES

Barb (Barbonymus balleroides Val. 1842) is one of the native species found in many rivers of Asian countries, including Indonesia. This species had higher commercial value compared with other fish species popular among consumers. In terms of supporting its domestication, information regarding the optimal aquaculture system of the fish is needed, one of which is its rearing location. Currently, there is limited information on rearing the fish at different locations with different altitude. This research aimed to obtain the growth of barb fingerlings reared in three locations with different altitudes. The study was conducted in the ponds located at Cijengkol area (ASL<200 m), Maleber (200 m<ASL<400 m), and Ciherang (ASL>400 m), West Java. Fingerlings of domesticated barb (total length 4.48 ± 0.10 cm; weight 0.95 ± 0.06 g) were stocked in three fixed net cages (size 2 m × 2 m × 1 m) in a pond (40 m × 20 m) at each location. Fish were fed with commercial feed (30% protein) of 5% biomass three times per day during 120 days of rearing. Water quality parameters observed were temperature, dissolved oxygen, and pH. Measured parameters were length gain, weight gain, specific growth rate, average daily growth, biomass gain, feed conversion ratio, and survival rate. The results showed that the fish reared in Maleber showed the best growth and feed conversion ratio compared to other locations (P<0.05). Meanwhile, no significant differences were found on the survival rate within all treatments. The growth of barb fingerlings is more optimal if reared in midland areas which have suitable temperature ranges for their growth.


INTRODUCTION
In terms of growth rate, altitude is correlated with the thermal gradients in the environment.Meanwhile, thermal gradients itself has significant influences on fish physiology prior to adaptation and maintain their stable conditions, such as metabolic rates and hydrodynamic body forms (Levinton & Monahan, 1983;Elliott, 1994;Taniguchi & Nakano, 2000;Jacobsen, 2008;Winemiller et al., 2008).Growth becomes a main parameter related to survival, longevity, and reproduction (Wootton, 1998;Hendry & Stearns, 2004).Several fish species showed growth variations as a result of their adaptation to different environmental conditions (Elliott, 1994;Nislow, 2000;Nicola & Almodovar, 2004).A variation on fish growth performance may reflect their temperature adaptation (Conover & Present, 1990;Conover et al., 1997), with each fish populations displaying faster growth at their optimal temperatures and lower growth at higher or lower temperatures.Barb (Barbonymus balleroides Val.1842) is one of the native fish species in Indonesia that exist in many rivers in Java and Kalimantan (Kottelat et al., 1993).The fish population is currently threatened by habitat destruction and overexploitation (Rumondang, 2013).Thus, it is necessary to domesticate this species to support their conservation as well as increase the aquaculture productivity in Indonesia.
According to Balon (2004), domesticated species are generally possessed for particular purposes, such as control their breeding and observed their behaviors, morphological, as well as its physiological variations.Teletchea (2017) suggested that animal domestication is a long and endless process in which animals become more adapted to human and captivity conditions.Based on domestication literature, some species have undergone this process for a long time and have reached level-5 for many years or centuries, while other species just had entered it (level-1 or 2).
In the process of domestication, aquaculture activities should be conducted to manage biodiversity and food security.However, information on optimal aquaculture system is required to reach that purpose.Certain fish species are able to adapt and grow well at different temperatures associated with altitude.Observation on growth parameters at different altitudes for barb culture could be important for aquaculture application.Several studies of fish growth in different locations have been conducted, such as in Pangasius (Tahapari et al., 2012), tilapia (Kusmini et al., 2011;Ariyanto & Listiyowati, 2015;Dereje et al., 2015), African catfish (Iswanto et al., 2015), salmon parr (Baum et al., 2004), turbot (Imsland et al., 2000), and brown trout (Parra et al., 2009).Recently, several studies on barb culture had been conducted for domestication program (Kusmini et al., 2016;Arifin et al., 2017;Radona et al., 2017).However, information on the growth variations of Barbonymus ballaroides at different altitudes has not been widely studied.Therefore, this study aims to determine the variation of fingerlings' growth in three locations with different altitudes.

MATERIALS AND METHODS
The study was conducted in pond facilities belonged to the Institute for Conservation on Inland Open-Water Fisheries and Ornamental Fish (BP3UIH), West Java, located in Cijengkol, Maleber, and Ciherang (West Java) from September 2016 to February 2017.The selection of test locations was conducted based on the altitude of each pond, where Cijengkol represented the low-altitude (<200 m above sea level), Maleber represented the medium-altitude (between 200 m and 400 m above sea level), and Ciherang represented the high-altitude (>400 m above sea level) culture environments (Figure 1).Barb fingerlings (total length: 4.48 ± 0.10 cm; weight: 0.95 ± 0.06 g) were stocked in three different fixed net cages (size: 2 m × 2 m × 1 m; stocking density: 750 fish/net) placed inside a 40 m × 20 m pond at each location.Fish were fed with commercial feed (30% protein) of 10% biomass per day with feeding frequency of three times per day.Data collections (length and weight measurements) were performed using random sampling from 30% of the total fish in each treatment and replication once in every 30 days during 120 days of the study period.Furthermore, length gain (L), weight gain (W), specific growth rate (SGR), average daily growth (ADG), food conversion ratio (FCR), and survival rate (SR) were calculated at the end of the rearing period.All of the growth parameters were calculated following the equations suggested by Effendie (2002) follows: Where L t represents the final length, L o is the initial length, W t is the final weight, W o is the initial weight, t is the duration of the study.F is the total amount of feed given during the study (day), N t is the final number of fish, N o is the initial number of fish.
Measured water quality parameters in the study included temperature and dissolved oxygen measured using dissolved oxygen meter (Trans Instrument HD3030), and pH measured using pH meter (Trans Instrument Senz pH Pro).Collected data were tested statistically using one-way analysis of variance (ANOVA).

RESULTS AND DISCUSSION
The results of water quality observations at each location indicated that water quality parameters (temperature, dissolved oxygen, and pH) were still within the normal ranges for barb.However, the water temperature showed significant differences between locations, with the highest found at Cijengkol and lowest found at Ciherang (Table 1).The optimum growth of domesticated barb was found at Maleber with an altitude of 200-400 m above sea level (Table 2).The growth parameter at Maleber differed significantly compared to the other locations (Cijengkol and Ciherang) (P<0.05).This result is also in accordance with a statement from Weatherley & Gill (1987) which stated that water quality is a variable that greatly affects the survival rate, reproduction, growth, management, and fish production.Temperature and dissolved oxygen Indonesian Aquaculture Journal, 13 (1), 2018, 7-12

Parameters
are the most important parameters in aquaculture systems.The optimum dissolved oxygen could increase growth and feed conversion ratio (Mallya, 2007).
Based on this research, the optimal condition for the growth of barb fingerling is in the midland areas.Different altitudes associated with water quality parameters affect the growth of fish.In this case, the temperature became limiting factors on the growth of barb, as reported by Weatherley & Gill (1987).These temperature differences would influence the food consumption, digestibility, and growth of fish through metabolic variation (Van Dam & Pauly, 1995;Gillooly et al., 2001), use of nutrients and energy (Azevedo et al., 1998;Buentello et al., 2000), as well as the activity of digestive enzymes (Ahmad et al., 2014).Temperature influence on fish growth has also been widely reported in several previous studies with different fish species (Jobling, 1993;Szczepkowski et al., 2006;Taufik et al., 2009;Wu et al., 2015).In the optimal temperature conditions, their metabolism and appetite will be optimum.Thus, it will have a positive effect on fish growth (Edwards et al., 1979;Kusakabe et al., 2017).
In this study, feed conversion ratio of barb in Maleber was lower than those of Cijengkol and Ciherang (P<0.05) because the midland location (Maleber) is more optimal for the growth of barb.Feed conversion ratio is the indicator to measure the effectiveness of feeding and feed quality used (Millamena et al., 2002).This result is consistent with the results of the Arnasson et al. (2009) which stated that maintenance of fish with optimal conditions and feeding techniques will result in better a feed conversion ratio.Furthermore, in terms of water temperature, several previous studies also revealed that an optimal rearing temperature affected feed conversion ratio of several fish species, such as turbot (Van Ham et al., 2003), Atlantic salmon (Handeland et al., 2008), cod (Bjornsson et al., 2001), and channel catfish (Buentello et al., 2000).Water temperature generally affected metabolic energy demands.Thus, the feeding rates are typically adjusted to meet the fish demands (Van Dam & Pauly, 1995).

CONCLUSION
The optimal location for the growth of barb (Barbonymus balleroides) is in midland areas (200 m < ASL < 400 m), because the water temperature in midland areas is relatively comfortable for barb compared to lowland or highland areas.

Figure 1 .
Figure 1.Map of rearing locations in this study.

Table 1 .
Water quality on rearing media of domesticated barb fingerlings (Barbonymus balleroides) reared on different altitude locations for 120 days

Table 3 .
Feed conversion ratio and survival rate of domesticated barb fingerlings (Barbonymus balleroides) reared on different altitude locations for 120 days ASL : Above Sea Level Description : Different superscript letters indicated significant differences between treatments P<0.05)