Assessment of Water Quality and Parasitofauna, and a Biometric Analysis of the Prussian Carp of the Romanian Lentic Ecosystem in Moara Domnească, Ilfov County

The aim of this study was to perform a morphometric analysis of Prussian carp individuals collected from the Moara Domnească pond in Ilfov County, Romania. This was accompanied by a physico-chemical characterization of the water, which was sampled from the same location. Consequently, we analyzed a total of 60 Prussian carp individuals that were caught in April (N = 32) and May 2023 (N = 28). For the <i>Carassius gibelio</i> in the study site, we provided, for the first time, data on the weight–length relationships (WLRs), the Fulton K condition factor and the biometric features, including the total length (TL), standard length (SL), head length (HL), snout length (SNL), body depth (BD), girth and ratios for the TL/HL, as well for the TL/BD and TL/SL. A negative growth type was estimated for both the samples of <i>C. gibelio</i>. Based on other studies and fishing reports, besides <i>C. gibelio</i>, there are another 11 species that belong to the <i>Cypriniformes</i> order, and there are two teleost members of the <i>Perciformes</i> order (<i>Lepomis gibbosus</i> and <i>Perca fluviatilis</i>)—these were also associated with this habitat. Water samples were collected from 12 sampling points (SP), which were subjected to physico-chemical characterizations that consisted of an assessment of the turbidity (T), pH, electrical conductivity (EC), chloride (Cl⁻), total hardness (TH), oxygen regime parameters, phosphate phosphorus (P-PO₄³⁻), nitrate nitrogen (N-NO₃⁻), nitrite nitrogen (N-NO₂⁻) and ammonium nitrogen (N-NH₄⁺) levels. In addition, considering their characteristics (high toxicity, non-biodegradability, long-range atmospheric transport and bioaccumulation potential), a number of organochlorine pollutants (OCPs) were identified. The total hardness values presented a very significant correlation with conductivity (r = 0.5974 ***) and with pH (r = 0.5854 ***). The results allowed for the water samples to be placed into the quality classes established by legislation, and they were also discussed in relation to the fishes’ requirements.