The present study investigates the variations in the feeding ecology of the knout goby (M.batrachocephalus). The index of relative importance indicated opportunistic feeding on macrobenthic fauna. The fish fed mainly on bivalves, fishes, amphipods and isopods. There were differences in diet composition during the years, seasons and sexes. M. batrachocephalus exhibited a generalist feeding strategy with a relative broad niche width.

knout goby --- feeding ecology --- benthos --- Black Sea

Despite advances in ichthyo-pathology of recent years, interpretation of fish serum biochemical parameters is often difficult by lack of reference values. That is why to know the value of the serum biochemical parameters can be a useful tool for monitoring health status, detecting illnesses and responses to therapy. This paper provides data concerning biochemical composition of carp serum (Cyprinus carpio) bred at Brateş Farm of Institute of Research and Development for Aquatic Ecology, Fishing and Aquaculture from Galaţi and Pleaşa Farm from Ploieşti, Romania. In research conducted onCyprinus carpio were determined following serum biochemical parameters: glucose (GLU), total proteins (TP), blood urea nitrogen (BUN), cholesterol (CHOL), triglyceride (TRIG), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P), iron (Fe).

carp --- biochemical parameters --- serum --- reference values

The paper presents some aspects regarding the influence of stocking density on the breeding of the common carp in a recirculating aquaculture system (RAS). The experiment covered a 30 dayperiod. It was conducted in four aquaculture tanks, 500 L/tank, in the recirculating aquaculture pilot system of “Dunarea de Jos” University of Galați. Two kind of stocking density variants were compared: 64 kg/m³ in V1 (B1, B3) and 32 kg/m³ in V2 (B2, B4). The stocking density was: 491 fish in B1, average weight - 65 g/ fish; 245 fish in B2, average weight - 66 g/ fish; 211 fish in B3, average weight - 152 g/fish; 107 fish in B4, average weight - 150 g/fish. The technological indicators obtained revealed the following: the specific growth rate (SGR), calculated as a mean value on the two repetitions, was 1.28%/day in V1 and 1.49 %/day in V2, indicating better growth in V2; the food conversion ratio (FCR), calculated as the mean value of the two repetitions, was 1.28 in V1 and 1.06 in V2, expressing a higher efficiency in capitalization of food in V2. The mean biomass gain in V1 was 30.46 kg/m³ as compared to 18.55 kg/m³ in V2, almost perfectly correlated with the stocking density. The daily growth rate (DGR) varied in a similar way, from 494.57 to 520.90 g/day in V1 and 302.4 to 315.9 g/day in V2. The experiment demonstrated a remarkable technological plasticity in both experimental variants, whereas, in terms of technological performance indicators, it was found that the application of lower stocking densities lead to higher crop biomass. The high stocking density means, therefore, large amounts of metabolic waste, removed from the breeding units through their effluent, the recirculating flow of which is 4m³/h, enough to ensure the whole volume of water in a growth tank to be changed every half hour.

common carp --- RAS --- stocking

The paper presents a comparative study regarding the evolution across time of the quality of aquatic eco-systems in the Crişuri Hydrographic Space (CHS), between 2007 and 2009. Having as a goal a real and complete image of the quality of the environment in the CHS, the ecological monitoringconducted was meant to observe the structure of the aquatic communities (macrozoobenthos, microphytobenthos, phytoplankton) and the biotope characteristics (physical and chemical parameters of water: pH, conductivity, dissolved oxygen, CBO5, CCO-Mn, CCO-Cr, nitrites, nitrates, phosphates, amonium, chlorophyll “a”, chlorides, sulphates, fix residues, As, Hg, Cu, Zn, Mn, phenols, detergents etc). The choosing of the monitoring sections, their identification and geographical position were accomplished in 2006. The basic criterion in the choice of the monitoring sections was the identification of all aspects that can influence the quality state of the waters. The monitoring of the quality state of the waters in the CHS was conducted in 40 sections, both on the main courses and their affluents, over a 3-year period. After the results of the analyses of physico-chemical and biological samples were obtained, the categorization of the prelevation sections in quality classes followed; depending on these classes, the modelation of the global ecological states of the watercourses in the CHS was realized by means of mapping techniques (GIS). Most of the monitoring sections were in the good ecological state category. The very good ecological state was determined only for those sections upstream all polluting sources. Nevertheless, some of the prelevation points exceeded both physico-chemically and biologically the limits of the good quality state, entering the category of moderate quality state. No watercourse in the CHS was determined for poor or bad quality state. Generally, a “preservation” of the quality state of the waters from one year to the following was noticed, although some monitoring points registered an improvement of the global ecological state, whereas others, a degradation. The improvement (eg. prelevation sections Râbiţa on Crişul Alb, Pădurea Neagră on Barcău or upstream Huedin on Crişul Repede) is mainly due to the lower quantity of mis-/untreated residual water upstream the monitoring sections. The modernization of waste-water purifying stations as well the connection of the urban areas to these stations finally contributed to the improvement of the water quality upstream these polluting sources.

bioindicators --- monitoring --- ecological state --- sources of pollution

Hematological indices are important parameters for the evaluation of fish physiological status. The aim of present study was to obtain a basic knowledge of the hematological response of Siberian sturgeon maintained in different technological condition induced by percentage of protein in feed. Specimens belonging to four experimental groups had individual weights of 135 g/fish, aged 5 months. The stocking density was 7.20 kg/m³ for the four variants; the fish biomass have been fed with ADVANCE BE 1 P granules with a protein content of 46 % for VE_46P, respectively ALLER CLASSIC granules with a protein content of 30 % for VE_30P (daily ration of 3 %). The sampling of Acipenser baeri blood from the four variants before and after the experimental trial allowed determination of hematological indices. Red blood cell counts (RBCc), haematocrit values (Hct), haemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were measured and analyzed, with routine methods used in fish hematology. Differences in hematological parameters were statistically analyzed by Student T test. Physiological stress induced by maintenance in different technological condition induced by percentage of protein in feed, is reflected in the hematological indices (significant decrease, p=<0.05, RBCc, Hb, MCV, MCHC) with direct implications at the biotechnological level.

Siberian sturgeon --- Acipenser baeri --- recirculating aquaculture systems --- red blood cell --- haematocrit --- haemoglobin concentration

t. In intensive fish farming systems in the recent years, under the multiplication of stressor factors, there is a trend of gradual increase in pathological disease whose etiologic agents are not appreciated at their real pathogenic value by fish farmers. Technological performance in classical aquaculture depends largely on the efficiency of disease control as well as stressful conditions. The subject of this paper was aimed at reducing losses in intensive aquaculture by applying efficient prophylactic and therapeuticmeasures, a good knowledge of parasitological diseases, their length, intensity degree and also the influence on the fish population being necessary. For these reasons, a complete ichtyopathological examination was done in the case of Asian cyprinid species, during 2007-2008 in the Carja 1 (Vaslui County, Romania) farm conditions, identifying the following parasitofauna: protozoa (ciliophora), plathelminthes worms (monogenea and trematoda) and crustaceans.

stressor factors --- parasitological diseases --- length --- intensity

t. The main purpose of the present experiment consists in evaluating the growth performances of North-American sturgeon larvae (Polyodon spathula (Walbaum, 1792)), raised in the recirculating system. Growth performance is influenced by many factors including food quality, quantity of food, culture species, fish size and water quality. The research was conducted between May 12^thto June 8^th,2010, in the pilot laboratory of Department of Aquaculture, Environmental Science and Cadastre of the Faculty of Food Science and Engineering, Galaţi. Ewos type growing unit (1.40 x 1.40 x 0.40 m) was populated with 1500 larvae with an age of 72-120 hours and with an average weight of 8±0.2 mg/larva. During the experiment the physico-chemical water parameters were within the admissible limit of sturgeons growth (temperature 4-26^oC, dissolved oxygen 5-14 mg L^-1, pH 6.5-8.5, N-N0₃^-1-20 mg L^-1,N-NO₂^-0-0.01 mg L^-1, N-NH₄⁺0.05-2 mg L^-1). The experiment results indicated a 78% survival and anindividual body biomass of 1.15 ± 0.21 g. The research goal is to achieve the following objectives:a.optimization of feeding parameters (ratio, fodders type and frequency) and the efficiency of different fodders types usage (conversion signs of fodders); b. providing the conditions for the biological material adaptation to the growth condition of the recirculating system.

Polyodon spathula --- recirculating sistem --- Tubifex sp. --- stocking density