Influence of abiotic and biotic environmental factors on weight gain of cultured carp on a carp farm

Abstract

During the period from April to October in the production season of the year 2000, seven chemical parameters of the aquatic environment were analyzed twice a month for the amount of natural food (zooplankton and bottom fauna) on pond No. 4 at the Dubica Carp Farm in Banatska Dubica (Vojvodina, Serbia). Correlation between natural food and carp growth was analyzed as well. The investigations revealed negative correlation between the amount of natural food per kilogram of ichthyomass and pH (p < 0.001, r = -0.875), electroconductivity (p = 0.0294, r = -0.673), COD (p = 0.0052, r = -0.782), total water hardness (p = 0.0186, r = -0.709), and carbonate water hardness (p = 0.0087, r = -0.758). However, statistically significant positive correlation was found between the biomass of natural food (g/kg of ichthyomass) and concentration of nitrates (p < 0.01, r = 0.841) and phosphates (p = 0.0427, r = 0.640). Concerning com­ponents of natural food (zooplankton and bottom fauna), bottom fauna biomass had a very low production and showed no statistically significant correlation (p = 0.137, r = 0.491) with total natural food biomass whereas zooplankton biomass was very significantly correlated (p<0.001, r = 0.830) with the total amount of natural food, indicating that zooplankton was the dominant component of natural food at the investigated fish pond. The daily weight gain (%) of cultured fish was greatest at the beginning of the carp farming season, i.e., in April, when it comprised a value of 2.3%. After negative growth at the end of May (-0.2%), a gradual increase of weight gain was recorded until the beginning of September. By comparing the biomass of natural food with the daily weight gain (%) of carp, it was observed that the weight gain had a trend similar to biomass of natural food with a 15 day interval. This relationship was justified by positive statistical correlation (p = 0.006, R = 0.960). As zooplankton was the major component of natural food, fish relayed on it as the main protein source showed by a significant positive correlation (p = 0.034, r = 0.907)

New data on the distribution and ecology of the mayfly larvae (Insecta: Ephemeroptera) of Serbia (central part of the Balkan Peninsula)

“…Similar results in this country were presented by Simić (1993Simić ( , 1995, Marković (1995Marković ( , 1998, Marković and Mitrović-Tutundžić (1997), Marković et al (1998), and Paunović et al (2006a), with the highest diversity observed in submontane regions as well, but with the lowest number of species in highland areas, which was not in accordance with our results. High diversity in watercourses of over 800 m could be explained by the fact that all study sites are near-pristine to reference, which mainly refers to the Timok and Južna and Zapadna Morava river basins.…”

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“…Semiintensive production is based on the use of natural food from the pond environment as the main source of protein and energy, only supplemented with additional feed when the natural production in the pond is deprived (Rahman, 2006;Marković et al, 2009a). Different grains or legumes (wheat, corn, barley, triticale, soybean, sunflower) are used as added feed, as well as formulated feed of different composition and level of treatment.…”

The effect of different supplemental feed types in semi-intensive production of common carp fry (Cyprinus carpio) on the structure and dynamics of pond ecosystems

“…na poĉetku sezone uzgoja. U tom periodu zabeleţene su vrednosti dnevne stope rasta šarana od preko 2% što je u saglasnosti sa rezultatima koje su Marković et al (2009a) dobili prilikom istraţivanja na ribnjaku ''Dubica'' tokom sezone uzgoja 2000. godine. U proleće i poĉetkom leta tek nasaĊena riba još uvek je nenaviknuta da uzima dodatnu hranu, pa je dobar rast u ovom periodu rezultat iskorišćavanja autohtonih izvora energije i materije iz prirodne hrane u ribnjacima.…”

“…Sliĉan trend porasta tvrdoće vode od poĉetka do kraja sezone uzgoja na šaranskom ribnjaku konstatuju Marković et al (2009a).…”

“…Kada je šaranu na raspolaganju razliĉita prirodna hrana, on bira bentosne invertebrate, a kada omiljena hrana postane malobrojna prelazi na ishranu zooplanktonom (Rahman et al, 2010). U zavisnosti od uzrasne kategorije šaran bira plen razliĉite veliĉine, ali krupniji šaran u drugoj godini proizvodnog ciklusa uglavnom 224 bira krupnije Cladocera kao što su vrste iz roda Daphnia -D. magna i D. pulex (Spataru et al, 1983;Dulić, 2007;Marković et al, 2009a). U većem delu sezone uzgoja u ribnjacima gde je šaran prihranjivan ţitaricama po broju jedinki dominirali su sitniji zooplanktonski oblici iz grupe Rotatoria, naroĉito vrste roda Keratella koji nemaju znaĉajnu ulogu u ishrani starijih kategorija šarana (Mitrović-Tutundţić, 1969;Adámek et al, 2004).…”