Qualitative and quantitative analysis of organochlorine insecticide residues were conducted in water, sediment, aquatic plants and animals from 3 freshwater reservoirs. Ninety water samples, 90 sediment samples, 397 aquatic plants samples and 121 aquatic animals samples were collected during March-April and August-September 1989. There were about 14 kinds of aquatic plants, such as water hyacinth, water lettuce, algae and water lilly etc. Aquatic animals are fish, shrimps and snails, but most of them are fish. They are striped snake-head fish, carp and catfish etc. Total samples of 698 were analyzed by using gas chromatographic techniques at Agricultural Toxic Substances Division. The results indicated that 5 kinds of insecticides were found in most samples. They were lindane, heptachlor, aldrin, dieldrin, DDT and derivatives. Dieldrin was detected at higher concentration and found in all samples. The residue level of dieldrin ranged from 0.01-0.12 ppb in water, 0.005-0.036 ppm in sediment, 0.001-0.138 ppm in aquatic plants and 0.001-0.037 ppm in aquatic animals respectively. The accumulation of dieldrin residue in water and aquatic plant samples from all reservoirs are not different but the level of dieldrin residue in sediment samples from Bueng Boraphed is higher than the other 2 reservoris. However the levels of dieldrin residue in sediment, aquatic plant and aquatic animal samples higher than those in water samples respectively.

Food composition of Abramis brama was studied in the shallow, meso-eutrophic Hamry reservoir (Czech Republic). Fish were sampled during the daytime in the pre-spawning period (April), the post-spawning (June), summer (July) and autumn (October) in 2011. The bream sampled comprised two main size groups: small (124-186 mm) and large (210-315 mm) standard length. Twenty specimens of each size group (except April - 40 large fish) were taken for analysis on each sampling occasion. Food composition was evaluated using gravimetric methods. Over the whole season, detritus and aquatic vegetation were the dominant dietary items taken. During summer, the diet of large bream comprised mainly aquatic vegetation. Benthic macroinvertebrates and zooplankton formed a minor part of bream diet over the whole season. Specific food habits of bream could be explained by specific conditions within the reservoir and available food resources.

Eric Baran, Eric Guerin, Joshua Nasielski, 'Fish, sediment and dams in the Mekong: How hydropower development affects water productivity and food supply', 2016

The monkey goby originating from the Ponto-Caspian area, has appeared in increasingly wide-spread areas of Hungary. In the Tisza-to water reservoir in North-Eastern Hungary along the Tisza River, 83 first summer samples of the fish were collected in the vicinity of Tiszafured on October 21st, 2000. The average length of the fish, not including the caudal fins, was 50,4 mm, the average weight was 2.1 g. Their alimentari canals contained mostly gnats (Chironomidae), but also the relative amount of the taxons Copepoda, Ephemeroptera, Ostracoda and Odonata was notable.

This paper focuses on the role of invasive, omnivorous/carnivorous amphipods in the food web of lakes and evaluates their significance as food items for fishes in two major lakes and reservoirs of the northwestern region of Russia: Lake Ladoga and Rybinsk Reservoir. Fish samples from both water bodies were collected, there age determined and their stomach content analysed to assess the role of the introduced amphipod in the diet. Fish species mainly analysed were: perch Perca fluviatilis, ruffe Gymnocephalus cernuus, burbot Lota lota, roach Rutilus rutilus, vendace Coregonus albula and kilka Clupeonella cultriventris. Analysis of original and literature data showed that the energy flow from zoobenthos to fish was modified by the Baikalian amphipod Gmelinoides fasciatus, introduced in the 1960s-80s into many lakes and reservoirs of Russia. The invader established successfully in different aquatic systems, rapidly reaching high abundances. Examples from Lake Ladoga and the Rybinsk Reservoir confirmed that the species is an important food item for littoral benthivorous fishes (ruffe, perch, gobies, burbot), especially at early ontogenetic stages and also for several pelagic fish (vendace, kilka). Although these fish species are considered low food quality, they enrich the food supply for large predatory fish species. In Lake Ladoga, G. fasciatus influenced negatively the abundance and biomass of native benthic invertebrates (including Gammarus lacustris and Asellus aquaticus) which were previously important prey items for littoral fishes: in the beginning of introduction up to 24100 m⁻² and 33.5 g m⁻²; after introduction 6200-7800 m⁻² and 16.5 g m⁻², respectively. At the same time, the invader uses food sources (chironomids and oligochaetes) that would otherwise not be available to fishes. Therefore, the introduction of G. fasciatus into lakes and reservoirs of European part of Russia led to a greater share of the benthic productivity available to fishes, thereby allowing the intensive use of new ecosystem components and increasing the overall production in these systems.