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In this study, a composite microwave absorber consist of barium hexaferrite (BaFe12O19) and Reduced Graphene Oxide (RGO) for Ku-band (12-18 GHz) was prosperous blend. Barium hexaferrite to arrange using the sonochemical method and at calcination temperature of 1000°C and a holding time of 1 hour. Subsequently, commercial RGO was composited with barium hexaferrite at a weight percentage of 6% RGO. The synthesized composite was characterized using X-Ray Diffraction (XRD) to analyze the formed phases, Raman Spectroscopy to confirm the presence of RGO in the composite, and Vector Network Analyzer (VNA) to evaluate the microwave absorption performance. The XRD test results show that there is no change in the crystal structure of barium hexaferrite due to the addition of RGO. The VNA test results showed that the addition of RGO could enhance the reflection loss value of barium hexaferrite. The BaFe12O19/RGO compound displayed a reflection loss value of -14.43 dB at a frequence of 16.50 GHz.

Intensive aquaculture can cause a high concentration of nitrogen compounds that affected water quality and the sustainability of cultivated fish. The purpose of this study was to evaluate the synergetic of nitrifying and denitrifying bacteria in controlling nitrogen compounds. The experiment was the combination among eight bacterial isolates based on in vitro. Four isolates of nitrifying bacteria (NP1, NP2, NP3, and NP4) and four isolates of denitrifying bacteria (DP1, DP2, DP3, and DP4). All of bacteria were inoculated at a density of 102 cells of each. The experimental design used was factorial with two treatment factors, namely four nitrifying isolates as the main treatment and four denitrifying isolates as sub-treatment and each treatment used three replications. The result of experiment showed that combination of nitrifying and denitrifying bacteria isolates which can utilizing ammonia, nitrite, and nitrate compounds very well found at combination of NP2 and DP1 isolates and NP2 and DP 2 isolates.

Nilem carp, Osteochilus hasselti is one of the local species which has an economic value in Indonesia especially the fingerling size “baby fish”. The purpose of this research is to determine the suitable of aeration rate for feeding incidence, survival, and growth. The aeration rates of this research were adjusted to A) 0 ml/minute; B) 500 ml/minute; C) 1,000 ml/minute; D) 1,500 ml/minute; and E) 2,000 ml/minute. Each treatment consisted of three replicates. 600 of newly hatched larvae (1 day old) were stocked in the fiber tank with size of 60 x 40 x 40 cm. Each fiber tank was completed by water heater. Larvae were cultured for 45 days. Larvae were fed Artemia and artificial diet. The parameters observed such as feeding incidence, survival, absolute weight and absolute length. The result showed that the aeration rate has influenced feeding incidence, the survival, absolute weight, and absolute length (P<0.05). The water quality parameter such as dissolved oxygen was affected by aeration rate where the higher of aeration will be led to increase the value of dissolved oxygen concentration. The aeration rate of 1,000 ml/minute is recommended to be suitable for larviculture of nilem carp in order to increase the seed production.

Magnetic nano particles, MnxMg1-xFe2O4 (x = 0.25, 0.5 and 0.75) with natural iron sand as raw material were successfully synthesized by co-precipitation method. The obtained samples were characterized by the x-ray diffractometer (XRD) and the vibrating sample magnetometer (VSM). The XRD result showed that the magnetic nano particles have a single phase of inverse-spinel face cubic center (fcc) structure. Furthermore, the lattice parameter constant, crystallite sizes and unit cell volume decrease with the increase of the x content. Contrary the dislocation density and lattice strain increase with increasing the x content. The VSM result showed that the saturated magnetization magnitude were getting high and the coercive field became low when the x were increased.

Magnetic nanoparticles of Fe3O4 (magnetite) have been synthesized from natural sand iron by co-precipitation method. The nanoparticles were synthesized using HCl as solvent and NH3 as co-precipitate. The nanoparticles synthesized at 70°C in two different treatments. Sample without Polyethylene Glycol (PEG) 6000 noted by A and sample with PEG 6000 noted by B symbol. The measurement that have been done for both samples were XRD (X-ray diffraction), FTIR (Fourier Transform Infrared) Spectrometry, SEM (Scanning electron microscopy), VSM (Vibrating sample magnetometer) and SAA (Surface area analyzer). The results showed that both samples were having Fe3O4 phases. Particle size, coercivity and magnetic saturation of B samples were smaller than A samples. But the surface area of B sample was larger than A sample. Both samples were then used to adsorb Cu and Pb ions using shaker method. Adsorption analysis from Atomic Adsorption Spectroscopy (AAS) showed that B was more effectivein adsorbing metal ions than A. The adsorption value of Cu and Pb ions were 79 and 91% respectively.

Molluscicide of fentin acetate (C 20 H 18 O 2 Sn) is commonly used at the present due to effective in terms to control of molluscs in the rice field. The aims of this experiment is to determine toxicity effect of fentin acetate on growth, productivity, and blood glucose on the common carp, Cyprinus carpio cultured at rice field water. A 12 of rice field plots with size of 25m 2 each were used. The stocking density of common carp was 25 fish/m 2 for each rice plot. The culture period of the common carp was 21 days. The different fentin acetate concentration as treatments were as followed M0) without molluscicide; M1) 0.375 g/L of molluscicide; M2) 0.75 g/L of molluscicide); and M3) 1.5 g/L of molluscicide. Statistical analysis using one-way ANOVA with three replicates for each treatment was performed. The result showed that the treatment of molluscicide at 0.75 g/L was significantly different to the others on survival rate and productivity (p<0.05). Application of 0.75 g/L of molluscicide showed a positive correlation on blood glucose value.

Nitrifying and denitrifying bacteria are very fruitful for controlling water quality in fish culture because they have a role in converting toxic chemical compounds into non-toxic compounds. The purpose of this experiment is to determine the isolates of nitrifying and denitrifying bacteria in terms of oxidizing ammonia, accumulating total nitrite, and accumulating total nitrate activities. Eight isolates of bacteria consist of four nitrifying bacteria (NP1, NP2, NP3, and NP4), and four denitrifying bacteria (DP1, DP2, DP3, and DP4) were inoculated with the density of 10 2 CFU/ml. The result showed that NP1, NP2, NP3, and NP4 isolates have almost similar ability to oxidize ammonium of 99.57, 99.37, 99.89, and 99.83%, respectively. The NP1-NP4 isolates on the total nitrite accumulated were 0.06, 0.05, 0.06, and 0.06%, while the total nitrate accumulated were 1.56, 1.65, 2.08, and 1.65%, respectively. The isolates of DP1, DP2, DP3, and DP4 can reduce total nitrate by 99.9, 100.0, 99.9, and 99.9%, respectively, while accumulated total nitrite was 0.01, 0.04, 0.00, and 0.00%. Isolates of NP2 and DP2 are recommended for controlling chemical compounds in the pond water.

Abstract Cichlid fishes exhibit rapid adaptive radiations with significant diversification rates in response to ecological variability, i.e., ecological opportunity or geographical isolation. The discovery of a Midas cichlid species in Lake Batur, Indonesia's largest volcanic lake, first reported in 2013, could represent such adaptations. Midas cichlids can now be found in a range of habitats in Lake Batur and dominate the lake's fish population by up to 60%. This study aimed to identify the interaction between habitat, water quality, and Midas cichlid in Lake Batur, facilitating morphometric variances in the fish populations. The fish were captured at five locations in Lake Batur using fishing rods, community nets with mesh sizes of 2–3 inches, experimental gillnets with mesh sizes of 1 inch, and fish scoops in floating net cages during August and November 2022. There were 46 fish samples caught from the five stations, all photographed using a digital camera and later measured using the ZEN 2012 software. The fish measurement employed a truss morphometric method using 21 distinct morphometric body features. Canonical analysis was used to determine the distribution of characteristics, while discriminant analysis was used to examine the closeness of association. The measured water quality parameters included pH, DO, temperature, conductivity, and TDS for in-situ and TSS, TP, TN, and chlorophyll A for ex-situ. The findings revealed morphometric changes among Midas cichlid species in Lake Batur caused by habitat and water quality differences. The distinction can be detected in the anterior and posterior bodies (C1, B1, C3, C6, C5, B3 and B4). Temperature and aquatic plants, Azolla pinnata, may detect the station and shape of fish in Lake Batur. Body shape cannot be identified by chlorophyll A, TN, DO, and TDS. Future genetic research could answer why fish groups with varied body types coexist in the same location. Resumo Os peixes ciclídeos exibem radiações adaptativas rápidas com taxas de diversificação significativas em resposta à variabilidade ecológica, ou seja, oportunidade ecológica ou isolamento geográfico. A descoberta de uma espécie de ciclídeo Midas em Lago Batur, o maior lago vulcânico da Indonésia, relatada pela primeira vez em 2013, poderia representar tais adaptações. Os ciclídeos Midas agora podem ser encontrados em uma variedade de hábitats no Lago Batur, onde dominam a população de peixes em até 60%. Este estudo teve como objetivo identificar a interação entre hábitat, qualidade da água e ciclídeo Midas no Lago Batur, facilitando variações morfométricas nas populações de peixe. Os peixes foram capturados em cinco locais no Lago Batur usando varas de pesca, redes comunitárias com malhas de 2-3 polegadas, redes de emalhar experimentais com malhas de 1 polegada e colheres de peixe em gaiolas de rede flutuantes, durante agosto e novembro de 2022. Foram capturadas 46 amostras de peixes nas cinco estações, todas fotografadas com câmera digital e posteriormente medidas no software ZEN 2012. A medição dos peixes empregou um método morfométrico de treliça usando 21 características morfométricas distintas do corpo. A análise canônica foi utilizada para determinar a distribuição das características, enquanto a análise discriminante foi empregada para examinar a proximidade da associação. Os parâmetros de qualidade da água medidos incluíram pH, OD, temperatura, condutividade e TDS para in situ, e TSS, TP, TN e clorofila A para ex situ. As descobertas revelaram mudanças morfométricas entre as espécies de ciclídeos Midas no Lago Batur, causadas por diferenças de hábitat e qualidade da água. A distinção pode ser detectada nos corpos anterior e posterior (C1, B1, C3, C6, C5, B3 e B4). A temperatura e as plantas aquáticas, Azolla pinnata, podem detectar a estação e o formato dos peixes no Lago Batur. A forma do corpo não pode ser identificada pela clorofila A, TN, OD e TDS. Futuras pesquisas genéticas poderiam responder por que grupos de peixes com tipos corporais variados coexistem no mesmo local.

Asian redtail catfish, Hemibagrus nemurus is one of the local species that have an economical values in Southeast Asia including Indonesia. The research aims to obtain the optimal of duckweed biomass as phytoremediation on survival, growth, stress response, and water quality dynamic of Asian redtail catfish culture. The different of duckweed, Lemna sp biomass as a treatments were as followed A) 0 gram (control); B) 20 gram; C) 40 gram; and D) 60 gram. Three replicates were performed for each treatment. 12 fiber thanks with size of 60 x 40 x 40cm were set up where each thank was stocking 50 fishes. The result showed that the Lemna sp biomass affect the survival, growth, biomass, and blood glucose (P<0.05). The absolute biomass of Lemna sp yield were also significantly different (P<0.05). Water quality dynamic during the culture such as nitrite, nitrate, total of ammonia, phosphate concentrations at the control (0 gram) was the highest compared to the others where the dissolved oxygen (DO), pH and temperature were relative constant. The Lemna sp biomass of 40 gram can be recommended as a phytoremediation for culturing seed in order to increasing productivity and keep the water quality in the optimal range.

The water quality can be improved by using probiotics as bioremediation. The probiotics are a consortium of nitrification and denitrification bacteria (Pseudomonas aeruginosa and Achromobacter insuavis), which both of the indigenous bacteria are the products of the Research Institute for Freshwater Aquaculture and Fisheries Extension (RIFA). The objective study is to determine the adding frequency of RIFA probiotic into the water fish pond of catfish culture concerning growth performance and survival. The catfish fingerling with a size of 7-8 cm long and weighing 16.45 ± 0.3 g was used. The stocking density was 750 fish/pond. Nine plastic sheet ponds with a water volume of 1.6 m3 and completed with aeration were used. A dose of probiotics was 10 mL/m3. The difference in adding the frequency of probiotic as a treatment was as followed: A) every 5 days; B) every 10 days, and C) without probiotics. The parameters measured survival rate (SR), absolute weight growth, specific growth rate (SGR), feed conversion ratio (FCR), water quality. One way ANOVA with three treatments and three replications were performed. The results showed that the use of probiotics could control nitrogen compounds in catfish cultivation, where the frequency of administration every 5 days gives the best results.