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DOI https://doi.org/10.18551/rjoas.2018-06.51
INFLUENCE OF FISH FEED AND DIFFERENT SALINITY LEVEL TOWARDS GROWTH OF STADIA GLASS EEL (ANGUILLA BICOLOR)
Sa'idah Nur Fitrotus*, Andayani Sri, Yanuhar Uun
Department of Aquaculture, Faculty of Fisheries and Marine Science, University of Brawijaya, Indonesia *E-mail: [email protected]
ABSTRACT
Eel (Anguilla sp.) is a type of fish that has high price point. It has been cultivated using both intensive and extensive cultivation system more particularly in Asia. However, mortality of the fish seed, more particularly during early cultivation stage, is still high. Objective of this study was to describe fish feed and salinity in order to optimize the fish growth. The size of the fish seed was between 3 and 5 centimeters. The seeds were kept in controlled container for 15 days. The density was 5 fish/liter and the salinity levels were 0 ppt, 5 ppt, 10 ppt and 15 ppt. The fish was fed with 5% of the total biomass of silkworm and paste twice a day. The observed parameters were quality of water consisting of pH, temperature, DO, ammonia, nitrate and nitrite. The finding showed that amylase enzyme activities reached the highest level when the salinity level was 5 ppt and the fish was fed with silkworm (natural fish feed).
KEY WORDS
Anguilla sp., salinity, fish feed, growth, glass eel.
Eel is a type of catadromous fish that requires certain level of salinity to survive. In addition, salinity is one of the factors that affect metabolism and enzyme activity in fish. Boeuf and Payan (2001) stated that salinity can affect activity of enzymes responsible for digesting food. Suitable salinity level will increase enzyme activity and at the opposite, inappropriate salinity level will decrease the enzyme activity. Effective metabolism and enzyme activity will produce energy fish needs to grow.
Growth is an important parameter of cultivation while survival is the parameter used to determine level of production. Growth is closely related to food because nutritious food will accelerate growth. Availability of natural fish feed has significant role in seed stadia. On the other hand, intensive cultivation requires artificial fish feed. Artificial fish feed can be manipulated as needed and in order to improve its quality. Artificial fish feed may consist of ingredients from plant and animals. Artificial fish feed producers should pay attention to nutrient content and size of fish that will consume the fish feed. Other parameters beside fish feed that affect eel growth are temperature, pH, dissolved oxygen, alkalinity and salinity (Anabela, et al., 2016).
The environment affects physiology, growth and survival condition of fish. In this context, the environment refers to salinity in which salinity influences physiology and biochemistry in fish growth. Salinity and temperature have complex interaction in controlling osmoregulation and growth. This process is also controlled by some active hormones and digestive enzymes. Osmotic balance is an external factor in aquatic biota growth (Liu, 2013).
Biomass is an element fish farmer should take into account in selecting fish feed. Suitable percentage of fish feed will accelerate fish growth. In this study, it can be concluded that type of fish feed has significant influence towards fish growth. Suitable type of fish feed will optimize the growth of eel seeds (Fekri, et al., 2014).
METHODS OF RESEARCH
Experimental study is type of research in which researchers manipulate one or more variables using particular methods; this method will influence the manipulated variables and also other variables. The manipulated variable is called independent variables while
dependent variable is a variable that depends on the independent variables (Setyanto, 2005).
Factorial design is a design in which one or two treatments are simultaneously tested. Factors commonly found in this design are genotype factors and site factors. The advantage is to describe influence of each factor and its combined effect (Zaki, et.al, 2014).
A1
B1
a
A2 B1
A1 B1 b
A1 B2 a
Kb
A2 B2 a
A2 B2 b
A1 B2 b
A1 B1 c
A2 B3 b
A1 B2 c
A2 B3 c
A2 B2 c
t >
A2 B1 c
A1 B3 a
A2 B3 a
A1 B3 b
Kc
A2 B1 b
A1 B2 c
Ka
Code K: control (0 ppt and natural fish feed) Code A: type of fish feed Code B: salinity
Codes 1, 2, 3: different type of fish feed and salinity Codes a, b, c: replication
Figure 1 - Research plan used in this study
Observations towards size (weight and length) of the samples were conducted every three days and the results were accumulated at the end of the observations to measure Sustainable Growth Rate (SGR). Quality of water is observed every day. Proximate test was conducted to describe nutrient content in the fish feed. The water is changed periodically in order to maintain its quality and provide suitable medium for the fish to grow.
RESULTS AND DISCUSSION
Growth of fish can be improved through selection, hybridization and genetic engineering. Among the three, genetic engineering is the most difficult method to improve fish growth due to the lack of gonad ripening, larval maintenance and spawning techniques researchers have (Tanaka, 2006).
Alatise and Effiong, 2013 stated that Specific Growth Rate (SGR) is daily growth rate of which formula is as follows:
SGR = (InWf-InWi) x 100 Time
Where: SGR = daily growth rate (gram/ day); Wf = average weight during treatment (gram); i = average weight in the beginning of the treatment (gram); Time = duration of treatment (day).
Based on the analysis towards the Sustainable Growth Rate (SGR), the most suitable salinity was 5 ppt and the most suitable fish feed was silk worm (Tubifex sp.). It happened because the other salinity levels or fish feed did not support the fish metabolism. As the result, the fish could not digest their food well and spent most of their energy to adjust to their environment.
Based on the proximate analysis, natural fish feed (Tubifex sp.) had better protein, fiber and fat content than the artificial one (paste). It showed that natural fish feed works more effectively to accelerate the fish growth.
a
Table 1 - Result of SGR Statistical Analysis
Code Salinity Fish Feed Result
K 0 ppt Silk worm 0.21±0.050 bc
A1B1 5 ppt Silk worm 0.33±0.042 c
A1B2 10 ppt Silk worm 0.32±0.035 b
A1B3 15 ppt Silk worm 0.21±0.036 a
A2B1 5 ppt Paste 0.17±0.006 c
A2B2 10 ppt Paste 0.05±0.010 b
A2B3 15 ppt Paste 0.05±0.000 a
The result showed significant difference (P>0.05); average ± STDEV.
0,35
K A1B1A1B2 A1B3A2B1A2B2A2B3
Figure 1 - Comparison of Growth Rate Percentage
Table 1 - Results of Proximate Analysis on the Fish Feed
Fish Feed Nutrient Content
Dry Ingredient (%) Ash (%) Crude Protein (%) Crude Fiber (%) Crude Fat (%)
Paste 97.61 19.43 41.77 0.51 8.77
Silk Worm 10.99 7.96 56.80 0.65 15.71
*) per 100 milligrams of sample.
Table 2 - Quality of Water and the Standardized Scores
Parameter Observation Standardized Score
DO 5.01 - 7.73 mg/l >4.5 mg/l
Temperature 27 - 30°C 23-30°C
pH 7.5 - 8.5 7.0-8.5
Ammonia 0.50 - 1.0 mg/l <1.0 mg/l
Nitrite 0.1 - 0.2 mg/l <0.2 mg/l
Nitrate 0.5 - 2.0 mg/l <2.0 mg/l
Salinity 5, 10, 15 ppt 5, 10, 15 ppt
During the treatment, the quality of water was observed periodically. The observations showed that the water was safe for aquatic organism. Table 2 described the observation results towards the water quality.
CONCLUSION
Based on the findings, it can be concluded that the most suitable level of salinity for eel (Anguilla bicolor) is 5 ppt and the most suitable natural fish feed for the fish is silk worm (Tubifex sp.).
REFERENCES
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