A fish pond experiment was conducted in two ponds which were stocked with 0 aged common carp and bighead carp larvae in numeric abundance ratio 3:1 (variant 1) while in other two ponds the ratio was 1:3 in favor of bighead carp (variant 2). To each of the two stocking variants we added one and the same number of 0 aged grass carps and 1+ or 2+ common carps. The experiment lasted 4 months (May to September) and was repeated in two consecutive years (2007, 2008). The second year variant 2 was conducted in three ponds. The fish ponds belonged to the experimental facilities of the Institute for Fishery and Aquaculture, Bulgaria. The plankton primary production and other related variables were measured approximately fortnightly and continuously throughout the experiment duration. At the end of experiment number and yield of fishes were measured and survival rates were calculated. Survival rate of bighead carp and yield of common carp and bighead carp of variant 1 were significantly higher than those of variant 2. The yield of bighead carp larvae did not, while that of common carp, grass carp and total fish yield correlated significantly and positively with plankton primary production. The yield of accidentally fallen into ponds of crucian carps (Carassius carassiusLin.) correlated strongly negatively with 1+/2+ common carps, which was indication for the strong food completion between them.

primary production --- fish ponds --- larvae

Faecal pollution of river water can lead to health problems because of the presence of infectious micro-organisms. These may be derived from human sewage or animal sources. Water safety or quality is best described by a combination of sanitary inspection and microbial water quality assessment. This approach provides data on possible sources of pollution in Arieş River water, as well as numerical information on the actual level of faecal pollution.

river --- water --- faecal pollution --- hygienic bacteria

Sixty two-year-old carps, Cyprinus carpio L. were kept in a closed water circulation system for five months. Fish were assigned to five groups (12 fish per group) and fed ad libitum on Aller Classic pelleted feed for carp: standard or standard pelleted mixture supplemented with 6% oils. The control group (I_K) received standard pellets, group II_S+Rz – sunflower oil + rapeseed oil (50% : 50%); group III_S+L – sunflower oil + linseed oil (80% : 20%); group IV_R – fish oil; and group V_SK – pork scratchings at the level of 6%. At the end of the experiment, 10 carps from each group were slaughtered and their body length and weight were measured to calculate mean body weight gains and mean individual gains. Fragments of intestine and hepatopancreas were histologically and morphometrically analyzed. The mean weight gains of fish at the end of the experiment, which were the highest for diet III_S+L, and the lowest for V_SK and I_K diets, were fully confirmed by histological analysis, which showed that the lowest gains in biomass and mean individual weight were due to digestive disturbances associated mainly with lipid metabolism. These disturbances did not occur in groups II_S+Rz, III_S+L and IV_R.

common carp --- fat-suplemented diet --- histology of intestine --- hepatopancreas

Receiver-bias hypotheses of signal evolution posit that male sexually selected traits evolve via prior selection for other functions. We found support for the hypothesis that the origin of female choice of mates is a linked effect of a receiver-bias for carotenoid coloration favored in the context of efficient food detection. Adult pentamorphic livebearing fish or pentas (P. parae) nibbled significantly more often at orange, red, and yellow discs than at green, blue, white, and black discs, outside a mating context. This innate attraction to carotenoid colored discs was positively correlated with female preferences for red and yellow melanzona males, and for novel red ornaments in fins of an immaculata male tested against typically uncolored immaculata. Furthermore, preference for carotenoid colored discs was absent in one ancestral taxon, and yet mapped onto a poeciliid phylogeny as ancestral. Overall these results suggest a strong association between a potential trigger of a mate choice preference and a sexually selected trait, thereby corroborating the receiver-bias hypothesis for carotenoid coloration independent and dependent of the assumptions of phylogenetic inference.

carotenoid coloration --- female mate choice --- phylogeny --- pleiotropic effect --- --- poeciliid fishes --- sensory-bias

Using invertebrate bioindicator species is one of the most important methodologies for evaluating the quality of the environment. The paper presents some data about monitoring studies, made during 1985-2008, with reference to some invertebrate bioindicator species, in the Someş River within the Cluj-Napoca city’s limits. A number of 16 systematic categories were highlighted. The results presented in this paper are the preliminary data for a wider study referring to the evolution of this aquatic ecosystem’s quality. On the other hand, the data show, for the studied period, a progressive increase of the level of the ecosystem’s aggression and pollution.

invertebrate bioindicators --- --- environment quality --- monitoring --- aquatic ecosystem