Vol 56, No 3 (2016)

Three oligo-raker species (≤19 rakers on the first gill arch) of the genus Melamphaes have been considered. A new species, M. papavereus, out of the group “M. typhlops” has been described from the Bay of Bengal of the Indian Ocean. M. simus and M. hubbsi out of the group “M. simus” have been revised. M. simus inhabits all oceans between 40° N and 40° S. M. hubbsi has been known from single specimens caught in the central part of the South Atlantic between 11° and 19° S.

New data on the maximum sizes and habitation depths for 83 species belonging to 15 families of demersal fish in the Russian zone of the Sea of Japan are provided on the basis of the results of the long-term studies conducted at the TINRO center.

Dietary preference and feeding ecology of Nematalosa nasus (Bloch 1795) in Chilika lagoon, India, was investigated through analysis of prey items in the guts and that in the habitat. Of the 230 taxa identified from the habitat in plankton samples from the lagoon, thirty five taxa were recorded from the guts of the fish. Index of Relative Importance showed 80% of the food comprised of microplankton groups viz. Foraminifera (35.79%), Chlorophyceae (20.52%), Bacillariophyaceae (12.30%), Cyanophyaceae (6.53%), other plant matter (3.65%) and Euglenophyaceae (0.76%). The fish is a generalized feeder on microplankton, with specialization on foraminiferans and Chlorophyaceae in Chilika Lagoon. Diet composition varied significantly with seasons. Prey type selectivity showed, preference to Gyrosigma sp. (α_i—0.98, e_i—0.85), Synedra sp. (α_i—0.47, e_i—0.71), Tabellaria sp. (α_i—0.58, e_i—0.47) and Ulothrix sp. (α_i—0.06, e_i—0.34) during monsoon and post-monsoonseason. Ammoniabeccarii (α_i—0.77 e_i—0.98), Campylodiscus sp. (α_i—0.04, e_i—0.17) and Microspora sp. (α_i—0.18, e_i—0.76), were selected during pre-monsoon period, which is also the peak breeding period of the fish.

The results of the studies on feeding of zander (Sander lucioperca) underyearlings in the Rybinsk Reservoir in 2008-2010 and 2012 are presented. The study revealed that, at feeding on plankton, the assemblage of the organisms consumed by juvenile zander has not been changed compared to 1950. The underyearlings prefer to feed on large zooplankters—Daphnia longispina, Leptodora kindtii, and Bythotrephes longimanus—along with copepods. At some sampling stations, the species of macrozoobenthos were included in the young zander food. The piscine component of zander food was dominated by underyearlings of Azov-Black sea tyulka (Clupeonella cultriventris); the fries of perch (Perca fluviatilis) and cyprinids (Cyprinidae) were less important. The feeding strategy of zander underyearlings was unchanged in various years. At turning to predatory feeding, not only the ratio of sizes of predator versus prey but also the proportion of the densities of their populations plays an important role.

A histological study of oogenesis of paliya Salvelinus alpinus complex (from larvae aged 3 weeks after hatching to the age of 3 years and 9 months) has been carried out. The fish was bred in tanks of the Federal Center of Fish Genetics and Selection (FCFGS, Ropsha, Leningrad oblast). Three-week-old larvae had primordial cells and gonia of the first orders in rudimentary gonads. Sex differentiation was completed and development of ovarian plates started in young fish aged 3.5 months. There were already previtellogenic oocytes in fish ovaries at this age. The morphology of the circumnuclear zone in previtellogenic oocytes of all stages, which appear as the age of the fish increases, as well as the morphology of oocytes of the period of trophoplasmatic growth, are described. In FCFGS conditions, paliya females aged 3 years and 9 months did not mature or oocytes degenerated in mature females. Only after a year, normal spawn was obtained from mature females.

The early developmental stages of capelin Mallotus villosus and lesser sandeel Ammodytes marinus were the major representatives of the fish larvae in the ichthyoplankton of the open waters of the White Sea in June 2007 and 2010 and in July 2010 and 2011. The larvae of these two species were widely distributed in the White Sea and have been registered in the large bays and in the other parts of the sea. The larvae of capelin and lesser sandeel were the most abundant in Onega Bay and in Dvina Bay and in Gorlo Strait of the White Sea; the larvae of lesser sandeel have also been found in the coastal waters of Kandalaksha Bay. The schooling of the larvae of these two species were characterized by a relatively permanent localization that referred to the spawning grounds; the shape and the location of the schoolings usually depend on the presence and configuration of the areas of the pronounced gradients of the hydrophysical parameters in these areas.

Separate and combined exposure of roach Rutilus rutilus embryos during the first 38 h after fertilization to magnetic field (500 Hz, 1.4–1.6 µT) and elevated temperature (23°?) causes morphological responses: decrease in mean values of length and weight of the body, increase in the number of vertebrae, and increase in the number of vertebral anomalies and morphological diversity of vertebral phenotypes. Size–weight characteristics and the number of vertebrae in underyearlings are related to the development of anomalies in its backbone. A method for counting of vertebrae in fish with backbone malformations is suggested.

Food searching behavior of the Buenos Aires tetra Hyphessobrycon anisitsi has been investigated before and after experimentally induced anosmia combined with visual deprivation. The threshold concentration of a water extract of familiar food (chironomid larvae) for fish with intact olfaction was 10^–6 g/L. Induced anosmia led to complete loss of the search reaction to food odor. The chemosensory behavioral response to the water extract of food used at high concentrations (10^-1-10^-2 g/L) was not restored in fish after 1.5, 5, or 13.5 months of anosmia. The obtained results show that the external sense of taste is absent or extremely poorly developed in the Buenos Aires tetra.

A new species Amblyeleotris memnonia sp. n. from the South China Sea is described. By the high number of rays in the second dorsal and anal fins, the new species is close to A. gymnocephala and A. cephalotaenia, but it differs from them and all other species by the uniform dark color of the body.