Carp Ponds Research Articles

ВОЗДЕЙСТВИЕ ИНТЕНСИВНОГО ПРУДОВОГО РЫБОВОДСТВА НА КАЧЕСТВО ВОДЫ В ПРУДАХ

The article focuses on the problem of obtaining high-quality fish products, for which it is necessary to take into account the specific conditions of each water body. Ponds intensively exploited for fish farming suffer from the violation of the hydrochemical regime of water, accumulation of a significant mass of phytoplankton and increase of organic pollution, which results in fish illness and death. The issues of participation of hydrobionts in the processes of reservoir self-cleaning and the influence of fish-breeding processes on hydrochemical and microbiological characteristics of water in the fish farms are being investigated. The work was carried out on the basis of two fish hatcheries in the Saratov region: “Engels Fish hatchery” LLC and “Teplovsky Fish hatchery” FSUE. Water samples for the study were taken from ponds with uterine population of carp and nursery ponds with polyculture of carp and herbivorous fish, carp monoculture and carp and white carp polyculture. It has been noted that the examined nursery ponds belong to the type mesosaprobic reservoirs. They have a powerful potential for self-purification. With the increasing number of bacteria involved in recycling of dissolved organic matter there is a decrease in biochemical oxigen demand and chemical oxygen demand. In the fish pond microorganisms that provide the processes of water self-purification find favorable conditions for their development and reproduction, especially in polyculture environment. The best indicators of biochemical oxygen demand were observed in ponds with a polyculture of carp and silver carp, because silver carp is a biological ameliorator of the aquatic ecosystem. Maintaining optimal balance between all parts of the hydrobiocenosis of the fishpond and the biochemical processes occurring with the participation of hydrobionts, which contribute to the purification of water, has a positive effect on the quality of water in the reservoir.

Investigation of bacterial diversity and pathogen abundances in gibel carp (Carassius auratus gibelio) ponds during a cyprinid herpesvirus 2 outbreak.

Cyprinid herpesvirus 2 (CyHV‐2) infection is detrimental to gibel carp health and may result in severe economic loss in freshwater aquaculture. However, information regarding the interaction of this pathogen with the aquatic environment is scarce. In this study, quantitative polymerase chain reaction (qPCR) and high‐throughput sequencing were used to determine the abundances of pathogens and bacterial community compositions in two aquaculture ponds in Jiangsu Province, China. The results indicate that the concentrations of six selected pathogens were higher in the water than in the sediment and that these concentrations peaked during disease outbreak. In total, 8,326 and 18,244 operational taxonomic units were identified from water and sediment samples, respectively. The dominant phyla were Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, and Chlorobi in water samples and Proteobacteria, Firmicutes, Actinobacteria, Chloroflexi, and Bacteroidetes in sediment samples. Bacterial communities were similar at the phylum level in different ponds, although significant differences were observed at the genus level. In addition, bacterial diversity was associated with environmental factors (temperature, chemical oxygen demand, NO2 −‐N, NO3 −‐N, and NH4 +‐N) in the pond where the outbreak occurred. Additionally, CyHV‐2 abundance was positively correlated with dissolved oxygen levels and Aeromonas spp. abundance in pond water (p < .01). This study provides comprehensive insight into the mechanisms of interaction between potential pathogens and the freshwater environment of aquaculture ponds during CyHV‐2 disease outbreaks. Furthermore, the results from this study can contribute to improvement of the aquatic environment and establishment of disease prevention and control measures.

К ВОПРОСУ РАЗРАБОТКИ ТЕХНОЛОГИИ ПРОДУКТОВ ФУНКЦИОНАЛЬНОЙ НАПРАВЛЕННОСТИ ИЗ ОБЪЕКТОВ АКВАКУЛЬТУРЫ

The article is focused on the strategy of scientific and technological development of the Russian Federation, which envisages the transition to a highly productive and environmentally friendly aquatic economy. The Concept of the fisheries development in the Russian Federation for the period up to 2020 defines the main objectives of the integrated state policy towards long-term development. The Concept formulates the goals, tasks, directions and ways of ensuring the interests of Russia in the field of efficient use of aquatic biological resources. According to the data of the Ministry of Agriculture and Fisheries of the Astrakhan Oblast, in 2018 there are about two hundred fish-water areas for the production of aquaculture facilities in the region. Carp species (including Romanian carp and common pond carp) occupy a leading place in aquaculture; their annual production in the Astrakhan region in recent years is over 50%. African catfish (Clarias) Clarias gariepinus is another promising aquaculture facility. In terms of the established chemical composition and functional and technological properties of the raw materials, in order to increase the stability during storage, to increase power intensity of the product made from this raw material and to expand the assortment by creating curative and/or prophylactic food products, the appointed aquaculture objects should be directed to manufacturing multi-component products functional purpose. Commissioning the technology of multicomponent functional products from the muscle tissue of aquaculture objects is an important direction, which allows using complex resource-saving technologies of balanced polycomponent food products of diabetic, dietary and gerodietetic purposes that meet the requirements of the existing technical documentation.

Analysis of Phytoplankton on The Common Carp (Cyprinus carpio) Pond and Tilapia (Oreochromis niloticus) Pond at IBAT Punten, Batu, East Java

Phytoplankton plays an important role in the aquatic ecosystem for supporting the survival of organisms, such as zooplankton and fish. The aim of this research was to observe the phytoplankton in the common carp ponds and tilapia ponds with water quality parameters at IBAT Punten, Batu, East Java. The survey method was used in this research. The water quality assay was temperature, brightness, pH, DO, CO2, Nitrate, and Orthophosphate, and the phytoplankton analysis was phytoplankton abundance, diversity index, dominance index, relative abundance, similarity index, and evenness index. The water quality on the carp ponds and tilapia ponds was quite good for common carp and tilapia growth. The average of phytoplankton abundance in common carp ponds were 1538 cell/ml which classified oligotrophic and tilapia ponds were 4900 cell/ml which included mesotrophic respectively, diversity index was moderate in both ponds, no dominance specific phytoplankton in both ponds the relative abundance in both ponds showed different phytoplankton availability, the similarity, and evenness index showed the same in both ponds and evenly on tilapia ponds and equally on common carp pond respectively. The carbon dioxide (CO2), nitrate, and orthophosphate have a strong correlation to phytoplankton abundance with value 0.882; 0.949; and 0.967 respectively. In the future, pond management will be needed in IBAT Punten with growing natural food.

Influence of the presence of ide Leuciscus idus on the boldness of common carp Cyprinus carpio

Behavioural traits (e.g., shyness vs boldness) can determine growth rates and also affect the probability of survival. We investigated behavioural changes in common carp caused by the co-occurrence of ide. The study was conducted in ten purpose-constructed experimental ponds containing both deep and shallow sections. Common carp (five individuals) were placed in each pond, but ide (two individuals of a variety called golden orfe) were placed in only half of the ponds. Three repetitions of the experiment were made, and in each repetition three observation series were conducted. Carp behaviour in every pond was noted during each series. Each observation lasted 5 min and the number of carp entries into the shallow water was counted. Each fish was used in only one repetition of the experiment. During eight of the nine observation series the common carp in ponds containing ide entered the shallow sections of the ponds significantly more often than carp kept without ide. Thus, the presence of ide influenced carp behaviour, making them bolder, which caused more frequent use of the shallow section of the ponds. We believe that carp were less stressed in the presence of ide. Thus, adding ide could be beneficial to carp, both in commercial carp production, because of the better use of the whole pond area, and also in ornamental carp breeding resulting in a higher visibility of fish.

Diffusive methane emissions from temperate semi-intensive carp ponds

Diffusive methane emissions from temperate semi-intensive carp ponds

Effects of fish farming on macrophytes in temperate carp ponds

Anthropogenic impacts on carp pond environments have increased over the last 100–150 years in Central Europe. Present semi-intensive carp pond management combines natural food resources, supplementary feeding and additional intensification measures such as manuring, liming, and winter and summer drainage. Despite increased eutrophication and fish stock pressure, many carp ponds still serve as habitats for threatened biota, including macrophytes. Both the ecologically essential role of aquatic macrophytes and the impacts that reared fish may have on them have been repeatedly reported in the literature; however, information is scattered and there exists no multidisciplinary synthesis of knowledge of fish farming and plant interactions for European carp ponds. In this review, we show that macrophytes from different ecological groups have specific demands regarding optimal ecological conditions (e.g. pH and trophy level); hence, they can act as indicators of a water body’s ecological status. Nevertheless, the overall ecological ranges of many species (i.e. the limits enabling their survival) remain rather broad. Moreover, interactions between the different elements within carp pond ecosystems are complex and change rapidly, facilitating the co-existence of macrophytes with contradictory ecological demands. As the literature suggests, carp ponds may play a role in biodiversity protection that is just as important (or even more so) than that of natural wetlands. Sustainable, environmentally friendly carp pond management is undoubtedly the best means of preserving the unique natural and cultural value of these aquatic ecosystems for the future.

Spatiotemporal variation of microbial community structure and physicochemical parameters in grass carp culture ponds

Microbes, as an important part of aquaculture ponds, can improve the recirculation of nutrients. This nearly 1-year-long study aimed to understand the factors and mechanisms that cause temporal changes in the concentration of microbiological indicators and nutrient concentration in the grass carp pond water of Chongqing Jiguan Aquaculture Limited. The study was comprised of five sampling campaigns, with samples spaced 2 months apart. Water temperature, dissolved oxygen and pH were measured in the field during sampling, and the concentration of nitrates, nitrites and phosphates were determined afterward in the laboratory. Subsequent analysis of 16s genome sequencing classified microorganisms into 32 phyla and 481 genera and revealed the core composition of the bacterial community for each season. Principal component analysis revealed that pathogens (Pseudomonas and Flavobacterium) are a significant negative correlation with water temperature and a positive correlation with ammonium concentration and dissolved oxygen. Bacillus and Streptomyces population size was negatively correlated with total phosphorus, while Lactobacillus and Bacteroides populations were positively correlated with water temperature and negatively correlated with ammonium salt. These findings reveal a significant relationship between microbial communities and the physicochemical parameters in aquaculture environments, providing a basis for further improving the aquaculture environment.

Life cycle assessment of common carp (Cyprinus carpio L.) – A comparison of the environmental impacts of conventional and organic carp aquaculture in Germany

The steadily growing aquaculture industry has been blamed for increasing environmental impacts at local and global levels. The greatest increase in production is expected for freshwater fish, such as carp and related species. Decisions on sustainable environmental management strategies in aquaculture should be based on quantitative analyses of their environmental impacts.In this study, Life Cycle Assessment (LCA) methodology was employed to compare the environmental impacts of conventional and organic common carp (Cyprinus carpio L.) raised in traditional pond aquaculture. Data collected in personal interviews with carp farmers in southern Germany was used for inventory analysis. Interviews with farmers showed that in practice, the key difference between organic and conventional production of carp lies in the sourcing of feed grains from certified organic versus conventional origin.The results of the impact analysis showed that conventional carp production has higher indicator values for climate change, ozone depletion as well as ionizing radiation (human health) and uses more water resources. Organic production led to higher acidification and an increase of over 100% in marine and terrestrial eutrophication compared to conventional production. Independent of the production system, feed and pond dredging (i.e., the effort of sludge removal from the pond using machinery) were the main contributors to many of the impact categories, apart from freshwater eutrophication, which was largely dependent on the carp farming stage. Therefore, the environmental superiority of one production method over the other depends on the impact category analyzed. A comparison with previously published LCAs of fish and meat products for the impact category of climate change shows that both, conventional and organic carp, have significantly lower indicator values than products from recirculating aquaculture systems or terrestrial animal products, such as beef. This finding, as well as the retention functions and ecosystem services provided by carp ponds, contribute to the environmental sustainability of both forms of carp aquaculture studied.Further efforts to increase the systems' sustainability should target the key areas of feed type and amount, frequency and method of pond dredging as well as the nutrient retention rate of carp, affecting potential emissions during harvest. Moreover, carp products with organic certification, wanting to uphold their claim of superior environmental friendliness, should address the critical issues uncovered in this LCA. Continuing methodological development, which acknowledges aquaculture specific impacts, will further increase the applicability of LCAs for products from aquaculture.

Spatial changes in zooplankton communities in a strong human-mediated river ecosystem.

River damming causes a decrease in water current velocity which leads to an increase in richness and abundance of organisms atypical for running waters. Zooplankton is a representative example of such organisms. The influx of zooplankton from carp ponds is an additional factor that increases richness and abundance of zooplankton in rivers. We hypothesized that zooplankton dispersing from the carp ponds colonize the impoundments in river and the richness of zooplankton increase in impoundments by development of new species, not observed in the upstream. The zooplankton was collected monthly from April to September of 2013 and 2014. Sampling sites were located in the Barycz river (in the lotic sections and in the dam impoundments), as well as in its tributaries, which are the outlets of carp ponds. The most changes in zooplankton richness and abundance were observed at sites located within the dam impoundments, especially in relation to the lower values of the current velocity. Since the abundance of pelagic rotifers, cladocerans and copepods in the carp pond outlets was similar to that at lower sites in the Barycz, the influence of the carp pond outlets on the abundance in the dam and lotic sections was significant. The river itself in its impounded sections provides advantageous conditions for retention and colonization by a high abundance of zooplankton dispersing from the carp ponds, and for the development of species not occurred in the upstream, which, in turn, increases richness.

Littoral vegetation improves the productivity of drainable fish ponds: Interactive effects of refuge for Daphnia individuals and resting eggs

Management of fish pond farming involves diverse practises aimed at increasing fish productivity, such as polyculture stocks, supplementary artificial feeding, adding nutrients, or drying ponds during winter or summer. Since aquatic vegetation has a positive influence on fish richness and biomass, aquatic plants could also have a positive effect on the fish productivity; however, its role has received little attention. Here, we conducted a study in which the productivity of carp was recorded in two ponds, one vegetated and the other with scarce coverage of aquatic plants. During winter, the ponds are dried, and are filled up with water in the spring. Then two-year-old carps are introduced to allow their growth until autumn when the ponds are drained and the fish harvested. The water used to fill the ponds contains no zooplankton organisms, so crustacean populations appear in the water column through the growth of hatchlings from resting stages deposited in the pond sediment during previous seasons. In order to explain patterns in fish productivity, crustaceans, which constitute an important element in the fish diet, were investigated. Particularly, the dynamics of the crustacean species were estimated during the spring and summer and, since cladoceran species are one of the main preferred preys of carp, body and clutch sizes of Daphnia were measured. Moreover, the density of cladoceran resting eggs in the sediment was estimated after the dry pond was filled, and just before the next pond filling. We found differences between vegetated and non-vegetated ponds. In the pond with aquatic vegetation (1) fish productivity was higher, (2) Daphnia species started to grow significantly earlier, had higher relative abundances, and delayed the population decline, (3) large sized European Daphnia galeata dominated over small sized American Daphnia parvula and Daphnia ambigua, and (4) the cladoceran resting egg bank was less eroded during winter when the ponds were dried. The results of this study indicate that macrophytes are likely to operate as a protection mechanism, not only for individual Daphnia, which keeps higher population densities and larger body sizes despite fish predation, but also protects the resting egg bank. This, in turn, was positively related to carp biomass. Accordingly, we consider that increasing macrophyte coverage should be considered in the management strategies for carp pond farming since littoral plant vegetation may act as a refuge for cladocerans as well as a productive ecotone improving the productivity of fish ponds.

Emergence of the Epizootic Ulcerative Syndrome in Pond Reared Carp Fish (Cyprinids) and It's Control Measure in Chitwan, Central Nepal

A survey on epizootic ulcerative syndrome (EUS) was carried in carp fish (cyprinids) reared in ponds during January 2016 to January 2017 at six locations of Chitwan, Nepal. Outbreaks of EUS were observed in 39.6% of the carp during winter. EUS infection was the most for Cirrhinus mrigala (47.3% of the 170 samples) and the least for Labeo rohita (12.3% of the 65 samples). EUS infected fish weighing range between 15g-300g were characterized as extensive deep ulceration on head, dorsal and lateral part of body and at caudal peduncle region. Histopathology examination of affected tissue of skin with adjacent muscles showed mycotic granulomas indicated a positive diagnosis for EUS. Survey results indicate that poor water quality in undrained ponds, uncontrolled entry of flooded water into the pond, runoff water from adjacent paddy field and use of contaminated equipment and seine nets were found to trigger risk for EUS infection in carp pond. Impact assessment of EUS showed that average economic loss due to EUS fish disease was 2257.92 kg/ha/year (33.01%) of the expected production. The highest economic loss of 1432.14 kg/ ha/year (53.53%) was estimated for large farm and lowest loss of 950 kg/ha/year (5%) for medium size farm. The simultaneous application of Ciphalexin in feed at 80mg.kg-1 biomass of fish for 15 consecutive days and two applications of Kohrsolin-TH at 900 ml/ha (1 m pond depth water) at weekly interval was found effective to control EUS infection in carps. The combined efficacy of these two drugs was estimated to be 97.7% control of EUS infection in carp fish. Int. J. Appl. Sci. Biotechnol. Vol 5(3): 313-320

Plasma proteins, hepatic enzymes, thyroid hormones and liver histopathology of Cyprinus carpio (Linnaeus, 1758) exposed to an oxadiazin pesticide, indoxacarb

Indoxacarb is a relatively new pesticide from oxadiazin class, which is used near carp ponds for agricultural purposes. Thus, the aim of this study was to determine indoxacarb effects on common carp (Cyprinus carpio). The fish were exposed to 0 (control), 0.75, 1.5 and 3 ppm of indoxacarb over 21 days and plasma biochemical characteristics and liver histopathology were examined. Exposure to indoxacarb induced fall in total protein after 21 days. Globulin increased after 7 days and then decreased after 14- and 21-day exposure. Plasma alanine transaminase and aspartate transaminase activities increased in 1.5 and 3 ppm treatments after 7-day exposure. Indoxacarb exposure significantly decreased plasma alkaline phosphatase after 7 days with no change at the second and third samplings. After 7 days, plasma T3 levels had no significant change; however, it decreased after 14 days in the 1.5 and 3 ppm treatments and also reduced after 21-day exposure to the 3 ppm treatment compared to the control group. Plasma T4 level only decreased significantly in the 3 ppm treatment compared to the control group after 21 days. Different histopathological symptoms such as necrosis, hyperaemia, sinusoidal space extension, pyknotic nuclei, leucocyte infiltration and melanomacrophage aggregates were observed after 21-day exposure to indoxacarb. The symptoms intensity was dependent on indoxacarb concentration. In conclusion, the present results show that indoxacarb exposure adversely affects common carp health and welfare, which consequently may induce serious problems in this species aquaculture.

ИЗМЕНЧИВОСТЬ РАЗМЕРНО-ВЕСОВЫХ ПОКАЗАТЕЛЕЙ И РЫБОПРОДУКТИВНОСТЬ ЧЕТЫРЕХЛЕТОК И ПЯТИЛЕТОК РУССКОГО ОСЕТРА, ВЫРАЩЕННЫХ В ПРУДОВОМ ХОЗЯЙСТВЕ РЕСПУБЛИКИ КАЗАХСТАН

The paper presents the analysis results of the body weight and length variability (body mass, zoological length, length up to the end of middle fin rays, fatness, mass-accumulation coefficient, growth), fish-productivity and gross-production in 4-year-old and 5-year-old Russian sturgeons ( Acipenser gueldenstaedtii , Brandt) cultivated in adapted ponds together with herbivorous fishes (grass carp ( Ctenopharyngodon idella ), silver carp ( Hypophthalmichthys molitrix ). The analysis helped to reveal some regularities about variability of 4-year-old and 5-year-old Russian sturgeons ( Acipenser gueldenstaedtii , Brandt) cultivated in artificial ponds adapted for carp breeding. The paper gives average values of body mass and length, variability characteristics, according to biological statistic parameters; analysis of absolute growth in different age groups of the Russian sturgeon cultivated at the pond carp farms. Gross-production values for 4-year-old and 5-year-old sturgeons are recommended to be taken as 337 and 450 kg/ga, correspondingly. It should be noted that 450 kg/ga is not considered as an ultimate gross-production value for the Russian sturgeon cultivated in the fish farms adapted for carp breeding.

First record of myxozoan parasites from fresh water fishes of Jammu and Kashmir and their pathogenecity.

The present study was aimed to isolate myxozoan parasites infecting the native carp Schizothorax esocinus (Heckel) and pond reared carp Labeo rohita (Ham.) collected from fresh water ecosystems of Jammu and Kashmir from July 2013 to June 2014. Various organs such as eyes, gills, scales, fins, intestines, visceral organs and pericardial cavity of as many as 100 live specimens were examined. Results revealed that 14% of the examined L.rohita were infected with Myxobolus rocatlae (Ham.) and 6% of S.esocinus (Heckel) were infected with M.kashmirensis sp. nov. Clinical signs revealed mucous laden gills while the parasitological observation under stereozoom binocular microscope revealed multiple minute plasmodia on the gills. On rupturing these plasmodia with sharp needle 100-500 myxospores were liberated. The identification to species level was done on the basis of morphological and morphometric attributes of the myxospores. This is the first record of myxozoan parasites in fishes from the state of Jammu and Kashmir, India. Histological observations of infected gills revealed plasmodia of two types (LV4 intralamellar vascular type) in M.rocatlae and (LV3 intralamellar vascular type) in M.kasmirensis causing necrosis, hyperplasia, hypertrophy and vacuolization of the epithelial and vascular endothelium.

Description of a new Neoactinomyxum type actinosporean from the oligochaete Branchiura sowerbyi Beddard.

Actinosporean infection of oligochaetes living in the mud of a commercial gibel carp pond with myxosporean disease was studied. Six actinospore types were detected exclusively from the oligochaete Branchiura sowerbyi Beddard with very high prevalence (18%). Five out of the six types were identified as the same actinosporeans described in previous reports, the sixth actinosporean was identified as a new Neoactinomyxum type and described here based on morphological and molecular characterisation. Spore body of the actinospore was globular, much smaller than caudal processes. Three caudal processes were disc-like in apical view, hemispherical in side view, closer together and encircling the spore body. The number of sporoplasm cells was detected as eight in one specimen. The new actinosporean markedly differed from other Neoactinomyxum types in literature having much bigger caudal processes. DNA sequence analyses further confirmed the morphological identification, and revealed the actinosporean described here (KU641392) possessed less than 94% sequence similarity with myxozoans available in the GenBank database.

Effect of different concentration of profitable Bacillus on bioremediation of common carp (Cyprinus carpio) pond discharge

Effect of different concentration of profitable Bacillus on bioremediation of common carp (Cyprinus carpio) pond discharge

Comparative analysis of using cereal grains and compound feed in semi-intensive common carp pond production

The semi-intensive system of carp farming is dominant in inland aquaculture. Although it appears to be simple, this system has a whole range of options, from those based on traditional rearing methods with use of plants from the region where the fish are reared to production based on the use of high-quality concentrated feeds. In this paper, we conduct a comparative analysis of the effect of using cereal grains as opposed to compound feed (pelleted and extruded) on the quantity of fish produced, flesh quality, histological changes in the digestive tract, water quality, and structure of the biocoenosis in the pond ecosystem. When the fish are fed cereal grains, production ranges from 500 to 1500 kg/ha, while using compound feed gives production that is twice as great. The proportions of protein and water are higher and that of lipids lower in flesh of common carp reared on compound feed in relation to fish fed cereal grains. Use of extruded feed gives better content of n-3 polyunsaturated fatty acids and a better n-3/n-6 ratio than when pelleted feed and cereal grains are used. Comparison of water quality in carp ponds under conditions of using various types of feed indicates that there are no significant differences. Although it was expected that feed with a higher percentage of proteins would cause disturbances in the aquatic ecosystem, their continual incorporation into the cycling of matter in the water contributes to maintenance of ecological equilibrium and even indirectly promotes growth of the common carp.

Supplementary feeding with thermally treated cereals in common carp (Cyprinus carpio L.) pond farming and its effects on water quality, nutrient budget and zooplankton and zoobenthos assemblages

To test the influence of supplementary feeding with thermally treated cereals on nutrient budget and environmental and biotic variables, three different treatments were applied in four experimental ponds: two with thermally treated cereals, one with raw cereal and a control with no supplementary feeding. Water parameters, zooplankton and zoobenthos were analysed from May to October over two consecutive years (2012 and 2013). In addition, nitrogen and phosphorus budgets were calculated as the difference between input (feed, stocked fish) and output (harvested fish). The results showed that type of supplementary feed had no influence on water quality, aside from water transparency. Ponds with added thermally treated cereal had significantly (P < 0.05) lower turbidity and suspended solids (and increased Secchi depth) compared with control. While no significant differences were observed in zooplankton assemblages between the experimental ponds and the control, macrozoobenthos density and biomass were considerably lower in the control pond. High seasonal fluctuations resulted in significant differences in density in 2012 only. The use of thermally treated cereal led to improved carp growth and nutrient budget, with an increase in carp yield and nutrient removal per hectare of pond surface. This result is a win–win situation with 10 % lower feed conversion ratio, increased profits and lower environmental impact.

Environmental quality and natural food performance at feeding sites in a carp (Cyprinus carpio) pond

Just like other domesticated animals, common carp (Cyprinus carpio) are able to learn where food can easily be obtained. As a result, carp in semi-intensive polyculture ponds could conceivably restrict their main activity centres to supplemental feeding sites, leading to lowered exploitation of natural food resources (zooplankton and macrozoobenthos) and localised degradation of environmental conditions. At two semi-intensive ponds in southern Moravia (Czech Republic), areas around feeding sites displayed significantly reduced oxygen concentration and saturation (mainly p < 0.001). Likewise, temperature, pH and transparency also decreased significantly at feeding sites (mainly p < 0.05), while turbidity increased. While there was no significant difference in zooplankton biovolume at feeding and non-feeding sites, zoobenthos density and biomass were significantly lower at feeding sites (mainly p < 0.01). The feeding behaviour of carp, therefore, led to significant changes in both abiotic and biotic conditions at supplemental feeding sites.