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Catfish is one of the fish that is in demand for cultivation activities because it has high market absorption, adequate nutrition, and is relatively easy to maintain. The research aims to analyze the hematological response of Sangkuriang catfish (Clarias sp.) after being given a feed substitute made from Duckweed flour (Lemna minor). The research was conducted in Palangka Raya City, Central Kalimantan Province. Feed from each treatment A (Commercial feed, feed without the addition of duckweed meal), B (Feed with 0% duckweed meal: 100% soybeans), C (Feed with 50% duckweed meal: 50% soybeans), D (Feed with 75% duckweed meal: 25% soybeans), and treatment E (Feed with 25% duckweed meal: 75% soybeans) was weighed at 5% of each fish's weight in the treatment container. The hematological response of Sangkuriang catfish given feed substitution made from Duckweed flour (Lemna minor) with parameters of hematocrit, leukocrit, hemoglobin, and blood plasma of Sangkuriang catfish for 45 days of research had a positive impact on fish health in this condition due to the content of Duckweed flour (Lemna minor). can help control the health of sangkuriang catfish.

Relevance. The studies are determined by the need to find the sensitive technogenesis indicators, which elemental composition can show the ecological and geochemical situation of the territory. Mercury have negative toxicological influence on living organism. Biological objects at the beginning of food chain could be informative and objective indicators of environmental situation and can have important information for further predictions. The aim of the research is to determine the indicator abilities of Lemnaceae family aquatic plants to the ecological and geochemical situation of various urbanized territories in Russia by studying concentration of mercury. Objects: an aquatic plant of the duckweed family (Lemnaceae), characterized by widespread occurrence, high biomass growth rate and tolerance to climatic environmental conditions. Methodology. The study was carried out according to a single methodology in 65 settlements from 46 regions of the Russian Federation. The determination of gross mercury in duckweed was carried out by atomic absorption spectrometry. Results. The role of aquatic plant of the duckweed family as a geo-indicator of technogenesis is considered. The distribution of mercury in macrophyte from the study area was discovered, the average mercury content in duckweed for Russia (average median – 14,7 ng/g, arithmetic average – 18 ng/g) was calculated. The abnormally high concentrations of mercury were determined in an aquatic plant from the Stavlopol Krai, the Republic of North Ossetia-Alania and Bashkorkostan, Kirov and Kemerovo Regions. The ecological and geochemical situation in these territories may be influenced by technogenic factors, such as chlorine-hydroxide production. The regional specificity of the Tomsk region were studied individually. The influence of the Northern industrial zone was particularly studied there.

Currently, duckweed is considered to be a cheap and effective way to treat wastewater from farm bioreactors. In addition to the environmental benefits, the productive duckweed biomass of the produced during wastewater treatment contains a high content of nutrients, especially protein that positions it as an additional ingredient in the feed of farm animals, poultry and fish. The influence of cultivation conditions of Lemna minor on protein synthesis taking into account the variation of nutrient concentration in wastewater are studied. The cultivation system combining an anaerobic bioreactor as well as the system of growing duckweed is used. Specific growth rate of duckweed, which was 2.68; 3.85 and 4.61 g/(m2/day) of the substrate concentration of 20, 40 and 60% respectively, is determined. The maximum growth density has been obtained (g/m2): 67.4 for 20% of the substrate on the 30th day;63.0 for 40% of the substrate and 66.0 for 60% of the substrate on the 27th day of cultivation. The dynamics of total Kjeldahl nitrogen content in duckweed has been studied. The greatest content of total nitrogen in duckweed grown on nutrient medium with 20% substrate concentration is observed on the 15th day with a maximum accumulation rate of 0.16 g/m2/day. On the 21st day ofcultivation in a substrate with 40% concentration a maximum total nitrogen is recorded at a storage rate of 0.20 g/m2/day; with a 60% wastewater content - at a rate of 0.24 g/m2/day. The dynamics of protein synthesis in the duckweed has been studied. In the course of the experiment it has been found that on the 16th day of cultivation the maximum percentage of protein content in the duckweed for 20% substrate is observed as 27.62%, while for 40% it is 28.13% and for 60% - of 29.14% to the 19-th day of cultivation. Based on the results of the studies, a mathematical model has been calculated, which can be considered adequate, and can be used to predict the protein content of the duckweed species Lemna minor depending on the nutrient concentration in the substrate and the duration of cultivation.