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In recent decades, the Amur sleeper (Perccottus glenii) is one of the most impressive east-to-west invaders of European inland waters, but there are insufficient data on its biology in the countries it has entered. Specimens of two sets of samples from November 2015 (n=25) and October 2016 (n=39) were caught in the Danube River channel near Veliko Gradiste (Serbia) by electrofishing. Thirty morphometric and eight meristic characteristics of the collected fish were measured with the aim of describing the general body shape in more detail using the ?point-to-point? method. This is the first attempt to obtain morphometric and meristic characteristics of Amur sleeper caught in Serbia. The results revealed a relatively low variability in the morphometric and meristic characters of the studied population. When compared to other studies, there was a great variability of the studied characteristics between geographically distant European populations that inhabit different water body types. Female fish had more robust bodies compared to males of the same length, while males had longer pectoral, anal and dorsal fins. Additionally, 2+ individuals had more robust heads and jaws, as well as longer anterior parts of the body compared to 1+ individuals of the same size

Paper description: We compared a model for spectral sensitivity data designed in our laboratory with the widely used template. Our model was designed with fewer (four) parameters, which we believe brings us closer to understanding the true nature of the absorption curve. In the fitting of spectral sensitivity data it uses non-transformed wavelengths. As a result, the shape of the curve remains the same for a broad range of l max values. Abstract: A four-parameter model of spectral sensitivity curves was developed. Empirical equations were designed for A 1 - and A 2 -based visual pigments with the main a-band maximum absorptions (l max ) from 350 nm, near the ultraviolet, up to 635 nm in the far-red part of the spectrum. Subtraction of the a-band from the full absorbance spectrum left a “b-band” described by a l max -dependent Gaussian equation. Compatibility of our templates with A 1 -and A 2 -based spectra was tested on the electroretinographic (ERG-derived) scotopic action spectra recorded in dogfish shark, eel, Prussian carp and perch. To more precisely estimate the accuracy of our model, we compared it with widely used templates for visual pigments. There was almost no difference between the tested models in fitting the above-mentioned spectral data. One of the advantages of our model is that in the fitting of spectral sensitivity data it uses non-transformed wavelengths and the shape of the curve remains the same for a broad range of l max values. Compared to multiparameter templates of other authors, our model was designed with fewer (four) parameters, which we believe can bring us closer to un derstanding the true nature of the absorption curve. https://doi.org/10.2298/ABS180822052G Received: August 22, 2018; Revised: November 7, 2018; Accepted: November 14, 2018; Published online: November 20, 2018 How to cite this article: Gacic Z, Mickovic B, Gacic L, Damjanovic I. New spectral templates for rhodopsin and porphyropsin visual pigments. Arch Biol Sci. 2018;71(1):103-10.

Pikeperch (Sander lucioperca), European catfish (Silurus glanis), burbot (Lota lota), and common carp (Cyprinus carpio) were collected from the Danube River (Belgrade section, Serbia), and samples of liver, muscle, and gills were analyzed for Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Se, Sr, and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES) to highlight the importance of species and tissue selection in monitoring research, contaminant studies, and human health research. The Kruskal-Wallis test revealed significant differences between fish species in regard to metal levels in liver, muscle, and gills. The principal component analysis (PCA) indicated that the studied fish species could be grouped on the basis of the level of analyzed elements in liver and gills. The Mann-Whitney test showed two subsets (one comprising two piscivorous species, pikeperch and catfish, and the other, two polyphagous species, burbot and carp) in regard to Cr and Hg levels in liver (higher levels in piscivorous species), as well as B, Fe, and Hg in gills (B and Fe with higher levels in polyphagous and Hg in piscivorous species), and As in muscle (higher levels in polyphagous species). Carp had distinctly higher levels of Cd, Cu, and Zn in liver in comparison to other three species. None of the elements exceeded the maximum acceptable concentrations (MAC). However, since Hg levels are close to the prescribed MAC levels, the consumption of these fishes can be potentially hazardous for humans.

In this study, 20 heavy metals and trace elements (Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Si, Se, Sr and Zn) were analyzed in different tissues (muscle, liver, intestine, feather and bone) of the great cormorant (Phalacrocorax carbo) and in different tissues (muscle, liver, gills, kidney and gonad) of their main prey (common carp—Cyprinus carpio and Prussian carp—Carassius gibelio) during the nesting season. Cormorant and fish specimens were collected at the Ecka Fishing Farm (Serbia) and from the nearby river. Principal components analysis (PCA) showed that cormorant livers were differentiated from other four tissues by higher concentrations of Hg, Fe, Cu and Mo, feathers by higher concentrations of Al and Si, and bones by higher concentrations of Sr and Mg. Differentiation among the three age classes of cormorants was observed only with regard to elemental concentrations in their feathers: subadult cormorants were differentiated by higher Hg and Zn concentrations, while the adults were separated by higher concentrations of Fe. In comparison with their prey (common carp and Prussian carp) cormorants were differentiated by higher concentrations of Fe, Hg and Cu in the muscle. Toxic mercury concentrations above 4 μg g−1 dw were determined in the liver of juvenile cormorants, as well as in the liver and feathers of subadults. Hg concentrations were significantly correlated among all studied tissues. Cormorant had significantly higher concentrations of Fe and Hg in muscle and liver than two studied fish species.

Three localities, representing three distinct coastal areas, were investigated: 1. the mouth of the Sutorina River; 2. the mouth of the Jaska River; 3. the mouth of the Bojana River (right branch). Regarding the composition of young mullet assemblages, Lisa saliens, Lisa ramada and Lisa aurata were dominant at the first locality; L. aurata and Chelon labrosus at the second; and at the third L. ramada was clearly dominant, Mugil cephalus occupied the subdominant position, while L. aurata was absent. The seasons of the first appearance of migratory fry were October, April, November, October and July, for M. cephalus, C. labrosus, L. ramada, L. aurata and L. saliens, respectively. Migratory periods varied from 2 (C. labrosus) to 7 (L. ramada) months.

In spectral sensitivity studies, electroretinograms (ERG) were recorded from the in situ eyecup of immobilized perch (Perca fluviatilis) electrofished in the floodplain zone of the Danube River. It is shown that the ERG b-wave is a good indicator of spectral sensitivity, although it reflects the activity of photoreceptors indirectly. With a maximum around 542 mm, the scotopic spectral sensitivity of perch obtained using fitted amplitude-log intensity functions for threshold calculation and two models developed in our laboratory for computer-assisted fitting of spectral sensitivity curves did not differ from the sensitivity determined using the microspectrophotometric and isolated pigment methods (maximum around 541 nm).

About 10000 huchen larvae, obtained by artificial spawning, were introduced on 28 May 1995 into the River Tresnjica, a tributary to the River Drina, using procedures applied routinely by local fishing associations. During next two months, only 33 fry were caught in the river. Nevertheless, valuable information has been obtained for the first time on young huchens in the Drina basin. The fry apparently selected slower or almost stagnant water habitats outside the main river course. The variability of prey organisms found in fry stomachs decreased with fry length. Larger and particularly motile prey, especially mayfly larvae, gradually dominated the fry diet. Also for the first time, we document homing instinct in huchens with mark‐recapture information: one out of the nine adults, tagged after spawning, was recaptured the following year at the same spawning site.

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