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This study aims to determine the results of the analysis of chess playing skills on mathematics learning outcomes for junior athletes of the Raja Kombi Trenggalek chess club. The research method used is a qualitative descriptive method with a quantitative approach. Participants in this study were 8 junior athletes of Raja Kombi Trenggalek chess club. Data collection techniques using interviews, skills results and documentation. The data analysis in this study used the mean and percentage formula. After analyzing the data, the results of this study concluded that in this study, the average score of playing chess skills was 85.00, then the average score of mathematics learning outcomes was 86.25. This is of course the higher the level of achievement of skills or intellectual intelligence, the higher the level of problem solving such as in learning mathematics. This is also influenced by motor and psychological aspects as a support for intelligence skills that affect the thinking of athletes. Then from the data analysis it can be said that the higher the level of achievement of chess playing skills, the higher the level of problem solving as in learning mathematics

Pollution of the freshwater ecosystem can cause adverse effects on aquatic organisms, especially fish. Fish skin is a multi-purpose tissue that serves as the first barrier to protect the fish from aquatic pollution and defense system against pathogens. Pangasiidae is an economically important riverine catfishes that generally exist in freshwater from the Indian subcontinent to the Indonesian Archipelago. Among genera in Pangasiidae, the genus Pangasius has numerous species. Indonesia has 14 strains of this fish and 3 of them, Patin siam (Pangasianodon hypophthalmus), Patin Jambal (Pangasius djambal), and Patin Pasupati (Pangasius sp.), are commonly cultured. This study aimed to characterize the skin of three Pangasius strains commonly found in Indonesia. The study was conducted at the Aquaculture facilities of the Research Center of Limnology. Three strains of Pangasius catfish were obtained from aquaculture farms. The fish were measured for the total length and body weight. The proportion of head, skin, bone, and meat was calculated. Collagen was extracted from the skin and was analyzed for type I, by ELISA methods. The thickness of the skin collagen was measured under a microscope after stained by the Masson Trichrome technique. ANOVA was conducted to evaluate the skin collagen content and skin collagen thickness. The result showed that there was no significant difference in collagen content among the fish strain, however, the collagen thickness was different.

Unionized ammonia (NH3) is highly toxic to freshwater organisms. Yet, most of the available toxicity data on NH3 were predominantly generated from temperate regions, while toxicity data on NH3 derived from tropical species were limited. Bada (Rasbora maninjau) as an endemic fish in Lake Maninjau-West Sumatra, has an important economic value for local communities. They live in clearwater with sand to gravel lake/river beds. The catch of R. maninjau is decreasing along with the decline of the water quality. Nowadays, the water quality of Lake Maninjau is declining as the effect of organic wastes from domestic sources and floating cage aquaculture. Therefore, the information about toxicity of ammonia in fish is important as a management tool for fish conservation. This research was aimed to find the LC50 value of ammonia in R. maninjau. A static acute toxicity test was conducted for 96 hours. Mortality was recorded for calculating LC50-96h, No Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC). Values of LC50-96h, NOEC and LOEC were 29.92 mg/L TAN or 0.7 mg/L NH3, 27 mg/L TAN or 0.63 mg/L NH3, and 38 mg/L TAN or 0.89 mg/L NH3, respectively. Maximum Acceptable Toxicant Concentration (MATC) of ammonia to Bada was 32 mg/l TAN or 0.59 mg/l NH3. The acute toxicity result showed that ammonia concentration affects the mortality of R manijau for 96 hours. The information about ammonia toxicity data will be used as a water quality guideline in Lake Maninjau.

Biofloc is one of the water bioremediation agents in aquaculture. A consortium of microorganisms in biofloc, which include heterotrophic bacteria, phytoplankton and zooplankton, can also function as natural food sources for aquatic biota. This study aims to investigate the potential of biofloc microorganisms consortium as natural food for commercial fish feed-less aquaculture. The study was conducted using Lake Maninjau water taken from two locations at Lake Maninjau, namely Nagari Sungai Batang and Nagari Maninjau, as test samples. Maninjau Lake was chosen because it had a high content of organic compounds and various microorganisms which could be used as an indigenous biofloc starter.Daphniasp. and Bada (Rasborasp.) were used as an experimental biota without periodical additional feed during the trial. The results showed that biofloc could grow well using Maninjau Lake water media. Bada and Daphnia could live in the biofloc system for 20 days without supplementary feeding and afterwards entering the death phase. The decline in the population of Bada and Daphnia was thought to be caused by the decrease of biofloc role as natural feed and its ability in maintaining the water quality.