Jurnal Lahan Suboptimal : Journal of Suboptimal Lands ISSN: 2252-6188 (Print), ISSN: 2302-3015 (Online, www.jlsuboptimal.unsri.ac.id) Vol. 11, No.2: 147-153 Oktober 2022 DOI: 10.36706/JLSO.11.2.2022.580 The Optimatization of Kissing Gourami (Helostoma temminckii) Fry Density in Recirculation System Culture Optimasi Densitas Benih Ikan Tambakan (Helostoma temminckii) dengan Budidaya Sistem Resirkulasi M Tansuka1, Ferdinand H Taqwa1*), Retno C Mukti1 Aquaculture Study Program, Fisheries Department, Agriculture Faculty, Universitas Sriwijaya, Indralaya, Ogan Ilir 30662, South Sumatra, Indonesia *) Corresponding author: ferdinand@fp.unsri.ac.id 1 (Received: 2 February 2022, Accepted: 29 July 2022) Citation: Tansuka M, Taqwa FH, Mukti RC. 2022. The optimatization of kissing gourami (Helostoma temminckii) fry density in recirculation system culture. Jurnal Lahan Suboptimal : Journal of Suboptimal Lands. 11 (2): 147-153. DOI: 10.36706/JLSO.11.2.2022.580. ABSTRAK Ikan tambakan (Helostoma temminckii) adalah jenis ikan rawa yang berpotensi untuk dibudidayakan. Peningkatan hasil produksi ikan tambakan dapat dilakukan dengan meningkatkan densitas. Permasalahan budidaya dengan densitas yang tinggi yaitu menurunnya kualitas air sehingga kelangsungan hidup dan pertumbuhan ikan tidak maksimal. Salah satu upaya untuk mengatasi masalah tersebut yaitu melalui pengelolaan lingkungan budidaya menggunakan sistem resirkulasi. Tujuan penelitian ini adalah untuk menentukan densitas optimal benih ikan tambakan pada sistem resirkulasi. Metode penelitian ini menggunakan rancangan acak lengkap (RAL) dengan menggunakan 4 perlakuan densitas ikan tambakan yaitu masing-masing 2, 3, 4, dan 5 ekor/L yang dilakukan dengan 3 ulangan. Parameter yang diamati meliputi kualitas air, pertumbuhan, tingkat kelangsungan hidup, dan kadar glukosa darah ikan. Hasil penelitian menunjukkan bahwa densitas terbaik ialah 2 ekor/L dengan pertumbuhan bobot mutlak 0,55 ± 0,02 g dan panjang mutlak 0,53 ± 0,04 cm, kelangsungan hidup 86,67%, kadar glukosa darah 50,67−52,55 mg/dL dan rasio konversi pakan 1,29. Nilai kualitas air selama pemeliharaan berada pada kisaran yang layak untuk kehidupan ikan tambakan, yaitu suhu 28,4−30,4°C, pH 6,6−7,4, oksigen terlarut 5,08−6,54 mg/L dan amonia 0,12−0,25 mg/L. Kata kunci: kelangsungan hidup, kualitas air, pertumbuhan, stres ABSTRACT Kissing gourami (Helostoma temminckii) is a type of swamp fish that has the potential to be cultivated. The increasing of yield for this fish can be done by optimization of stocking density. The problem of aquaculture with high stocking density is decreased water quality, growth and fish survival. One of the efforts to overcome this problem is through the management of the cultivation environment using a recirculation system. The purpose of this study was to determine the optimal density of kissing gourami fry on a recirculation system. This research method used a completely randomized design (CRD) using 4 treatments of fish stocking density (2, 3, 4, and 5 fish/L, respectively), which was carried out with 3 replications. The parameters observed included water quality, growth, survival 148 Tansuka et al.: The Optimatization of Kissing Gourami rate, and fish blood glucose level. The results of this study indicated that the best density was 2 fish/L with absolute weight growth was 0.55 ± 0.03 g, absolute length growth was 0.53 ± 0.05 cm, survival rate was 86.67 %, blood glucose levels were 50.67−52.56 mg/dL and food conversion ratio was 1.29. The water quality value during the fish rearing was in the appropriate range, i.e. temperature 28.4−30.4°C, pH 6.6−7.4, dissolved oxygen 5.08−6.54 mg/L and ammonia 0.12−0.25 mg/L. Keywords: growth, stress, survival, water quality INTRODUCTION 2016). High fish density during rearing can cause fish stress, resulting in a decrease in Kissing gourami (Helostoma temminckii) body resistance and the long term can cause is one of the freshwater fish that is often death. Segovia et al. (2012) declared that in found in several areas of Southeast Asia the high density culture is required water (Sugihartono, 2014). Kissing gourami have quality management to remove metabolic a high economic value because apart from waste and reduce the risk of oxygen being used as consumption fish (fresh and depletion. processed), they also have the potential to One alternative in managing water be traded as ornamental fish in several quality in fish culture media is to use a countries. This fish is easy to breed, grow recirculation system. This is in accordance fast, and is one type of ornamental fish that with the statement of Jubaedah et al. (2020) has a potential demand in Bangladesh that the recirculation system could (Hossain & Mohsin, 2021), Australia, minimize water changes and maintain water North America, Europe, Japan (Wildayana quality. The water recirculation system can & Armanto, 2021), India (Jena et al., 2019), be supported through physical, chemical, as well as Thailand, Philippines and and biological filtration, which functions to Malaysia (Kottelat, 2013). maintain water quality (Hastuti et al., 2017). To meet the increasing demand for One of the filter materials used is charcoal. human consumption of fishery products, The use of charcoal can significantly especially kissing gourami commodities, improve water quality by reducing the aquaculture activities are needed. Kissing content of nitrogen, ammonia, nitrite, gourami farming with high density is able phosphate. (Schmidt et al., 2019). Research to produce higher fish production. However, conducted by Raharjo et al., (2016) showed the problem faced in high density that the optimal density for kissing gourami aquaculture is a decrease in water oxygen with a size of 3−5 cm and a weight of 1.4 g levels and an increase in fish metabolic is 2 fish/L. products. Metabolic products and excess In that study, the density of more than 2 feed residue, especially in high density fish fish/L showed a lower value of growth and culture, can cause a decrease in water survival rate of fish. Therefore, it is quality in the culture media. Poor water necessary to do further research to increase quality causes the fish's appetite to decrease the production of aquaculture with higher so that fish growth will be slow and can density optimization, so that it still supports result in fish death (Raharjo et al., 2016). the growth of kissing gourami (H. In addition, the high fish density will temminckii) in the recirculation system. have an impact on changes in the behavior This study aimed to determine the optimal and physiological conditions of fish due to density of kissing gourami (H. temminckii) competition in space utilization size of 4.05 ± 0.5 cm in a recirculation (Sukmawantara et al., 2021). If this system, so that water quality can be condition continues, it can cause changes in maintained in a proper condition, and it can fish health conditions so that survival and still support the survival and growth of growth will be hampered (Raharjo et al., kissing gourami optimally. Jurnal Lahan Suboptimal : Journal of Suboptimal Lands 11(2) Oktober 2022 149 MATERIALS AND METHODS stocking the fish, the fish were acclimatized for 5 minutes to adjust the water Materials temperature in the plastic bag and the The materials used in this study included aquarium. The rearing of fish was carried kissing gouramy fry (length of 4.0 ± 0.5 out in a controlled system by feeding 5% of cm), potassium permanganate, charcoal as a body weight with a frequency of feeding filter medium and commercial pellets with a three times a day, at 08.00, 12.00, and protein content of 40%. The tools used in 16.00 in local time for 30 days. A sampling this study include an aquarium (measuring of fish length and weight was carried out 23 x 23 x 23 cm3), thermometer, water once a week. Blood glucose levels were pump, PVC pipe (⌀ 0.5 and 4 inch), DO measured at the beginning and the end of meter, pH meter, digital scale, aeration hose, the study by taking 2−4 µL of fish blood aeration stone, filter, aquarium pipe (⌀ 16 samples from 10% of the number of fish mm), pipe connector (⌀ 16 mm to 0.5 inch), from each treatment container and then blower, spectrophotometer and Gluco kit tested using the Gluco kit Test. test. Research Methods This study was designed using a completely randomized design with four treatments and three replications. The treatment applied was as follows: P1 : Rearing of kissing gourami fry with a density of 2 fish/L P2 : Rearing of kissing gourami fry with a density of 3 fish/L P3: Rearing of kissing gourami fry with a density of 4 fish/L P4 : Rearing of kissing gourami fry with a density of 5 fish/L Procedure Preparation of Fish Rearing Containers The container used were 12 glass aquariums which were arranged according to a random treatment code. The prepared aquarium was filled with 10 L of water, then a filter unit was installed and aeration was given. The filter used was a charcoal with a volume of 1.6 L based on the modification of Tanaya and Prihatmo, (2021). After that, the system was stabilized by flowing water for 1 week, so that the nitrifying bacteria increased in the filter media. The filter design in this study was presented in Figure 1. Rearing Fish were stocked into the aquarium according to the density treatment. Before Figure 1. Recirculation system unit Data collection Absolute Length Growth The formula used to calculate the absolute length growth of fish was (Firdaus & Mukti, 2021): L = Lt – L0 Note: L : Absolute length growth of fish (cm) Lt: Fish length at the end of rearing (cm) L0: Fish length at the beginning of rearing (cm) Absolute Weight Growth The formula used to calculate the absolute weight growth of fish based on Firdaus and Mukti (2021) was: W = Wt–W0 Note: W : Absolute weight growth of fish (g) Wt: Fish weight at the end of rearing (g) 150 Tansuka et al.: The Optimatization of Kissing Gourami W0: Fish weight at the beginning of rearing (g) Survival Rate The calculation of the percentage of fish survival based on Firdaus and Mukti (2021) was: SR = x 100 Note: SR : Survival rate (%) Nt : Number of fish at the end of rearing N0 : Number of fish at the beginning of rearing FCR (Feed Conversion Ratio) Calculation of feed conversion ratio based on Azaza et al. (2014) was: FCR = Note: FCR : Feed Conversion Ratio Wt : Final fish weight (g) W0 : Initial fish weight (g) D : Total of dead fish weight (g) F : Amount of feed given (g) Fish Blood Glucose Levels Measurement of blood glucose levels of fish using the Gluco kit Test. Data analysis The water physical and chemical values obtained from each treatment include temperature, pH, dissolved oxygen, and ammonia were analyzed descriptively. Data on growth, survival, blood glucose levels, and feed conversion ratio were analyzed by analysis of variance test at a 95% confidence level. A further test of Honestly Significant Difference (HSD test) was carried out if there was a significant difference between the mean treatment values. RESULTS Data on absolute weight and length growth of kissing gouramy fry during the rearing period with a recirculation system were presented in Table 1. The data in Table 1 showed that the highest absolute growth of cultured fish was found in treatment P1 with an average absolute weight growth of 0.55 ± 0.02 g and an absolute length growth of 0.53 ± 0.04 cm. Based on the results of growth, it is known that rearing kissing gourami with a density of 2 fish/L produces the best growth and is significantly different when compared to treatments P3 and P4 (4 and 5 fish/L). Table 1. Growth of absolute weight and length of kissing gouramy fry Average Value of Absolute Growth Treatment Weight (g) Length (cm) (HSD0.05 = (HSD0.05 = 0.10) 0.040) P1 0.55 ± 0.02c 0.53 ± 0.04b b P2 0.49 ± 0.01 0.47 ± 0.03ab a P3 0.44 ± 0.01 0.41 ± 0.03a a P4 0.43 ± 0.00 0.38 ± 0.03a Note: Means followed by different superscript letters in the same column show significantly different results at the 5% level. The survival rate of kissing gourami at the end of the rearing period showed that the treatment with a density of 2 fish/L gave a higher survival rate than the other treatments (Table 2). However, the results of the analysis of variance showed that the treatment had no significant effect on the survival rate of kissing gourami. Table 2. The survival rate of kissing gourami fry Treatment Survival Rate (%) P1 86.67 ± 2.35 P2 85.56 ± 1.57 P3 83.33 ± 1.17 P4 82.00 ± 0.00 The feed conversion ratio at the end of the rearing showed that the treatment with a density of 2 fish/L resulted in a low feed conversion ratio value of 1.29 and the highest feed conversion at P4 (5 fish/L) with a value of 2.03 (Table 3). The results of the HSD test showed that the treatment of P4 was significantly different from the other treatment. Jurnal Lahan Suboptimal : Journal of Suboptimal Lands 11(2) Oktober 2022 Table 3. Feed conversion ratio Feed Conversion Ratio (HSD 0.05 = 0.54) Treatment P1 1.29 ± 0.057a P2 1.55 ± 0.13ab P3 1.82 ± 0.09ab P4 2.03 ± 0.34b Note: Means followed by different superscript letters in the same column show significantly different results at the 5% level. The blood glucose level of the kissing gourami fry at the end of the rearing showed that the treatment with a density of 2 fish/L resulted in the lowest blood glucose level of 52.55 mg/dL and was significantly different from the other treatments (Table 4). The highest blood glucose levels were found in the treatment with a density of 4 fish/L (P4) which reached 95.66 mg/dL. Table 4. Blood glucose level of kissing gourami fry Treatment Blood Glucose Level (mg/dL) End Rearing Initial (HSD0.05 = 11.78) P1 P2 P3 52.55 ± 0.955a 50.67 65.22 ± 3.55b 85.33 ± 1.44cd P4 95.66 ± 7.24d Note: Means followed by different superscript letters in the same column show significantly different results at the 5% level. The results of water quality measurements which include temperature, pH, dissolved oxygen, and ammonia are presented in Table 5. Table 5. Water quality during the rearing of aquaculture fry Range Optimum Variable Value Range* OC Temperature ( ) 28.3−30.5 20−35 pH 5−9 6 −7.9 Dissolved oxygen >3 (mg/L) 3.11 – 6.54 Ammonia (mg/L) 0.10− ≤ 0.25 <1 Note: *: Arifin et al. (2017) 151 DISCUSSION Differences in fish density during the rearing period caused a significant effect on the growth of absolute weight and length of kissing gourami. An increase in the density of kissing gourami during rearing showed the opposite pattern to the growth of absolute weight and absolute length of kissing gourami at the end rearing. This is related to the competition for higher space utilization so that it will trigger higher stress levels. According to Rahmawan et al. (2020) stress from high stocking densities can increase energy requirements for maintenance so as to reduce energy for growth. The energy used by fish to maintain this homeostatic condition will be higher if the physiological load is greater due to the higher density of fish. Mukti et al. (2019) stated that growth occurs when there is an excess of energy from the feed consumed by fish after the needs for metabolism are met. As the density increased, the growth of absolute weight and absolute length of kissing gourami fry decreased. The existence of competition in the utilization of higher space and feed capacity in fish culture with higher density will cause the allocation of energy needed in the homeostatic process is greater. Such conditions can trigger stress in fish that will cause a decrease in survival. Raharjo et al. (2016) stated that high density makes the space for the fish narrower, thus placing an excessive burden on the fish. The impact of this stress can cause decreasing physiological performance until the death. Based on observations during the rearing period, it was shown that the feed conversion ratio increased with increasing density. Raharjo et al. (2016) stated that at a lower density will result in higher growth due to lower feed competition, so that the energy allocation for growth will be greater. This is associated with a lower feed ratio value. The lower of the feed conversion ratio value showed the better utilization of feed for growth. According to Fry et al. 152 Tansuka et al.: The Optimatization of Kissing Gourami (2018) the value of a fairly good feed conversion ratio in cultured fish generally ranges from 1.0 to 1.4. On the other hand, the growth of cultured fish is closely related to the physiological conditions and aquaculture environment. The results of the measurement of blood glucose levels of kissing gourami showed that it increased with increasing density. Prihadi et al. (2017) stated that an increase in density can cause stress, which is indicated by an increase in blood glucose levels, so that it can inhibit growth and even death. According to Andrade et al. (2015) fluctuations in blood glucose levels in fish indicated the ability of fish to use energy sources from glucose to maintain their ideal conditions against the burden of changing environmental conditions. This is influenced by several factors, including the duration and intensity of the stressor, species, stadium, and endurance of the fish itself. The results of the physical and chemical water measurement showed that the management of the water quality of the culture media during the rearing period had been able to support the survival of kissing gourami which was quite high. Arifin et al. 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