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The Yangtze is the largest river in China and the third largest river in the world. Being pregnant with plentiful fish resources, it is not only the representative of the areas with biological diversity, but also a cradle of freshwater fisheries in China. In the Yangtze, at present, the fishery resources are seriously depleted; the fishery yield by fishing is significantly reduced; significant changes have occurred on the structure of fish community, with decrease in migratory fish species, reduction in the quantity of the populations of rare, peculiar and economically important fish species and increase in the number of exotic fish species, and severe trend in fish stunting. Habitat fragmentation and shrinkage, resources overexploitation, water pollution and invasion of exotic species are the main causes for threatening fish stocks in the Yangtze River. Since 1950’s, a lot of scientific researches have been conducted on biology of fishes from the Yangtze River and its fisheries to provide scientific basis for their protection. In recent years, measures such as closed spring, fish reserves, artificial enhancement & release, ecological rehabilitation, fishery management and international cooperation have played important roles. Nevertheless, researches on fishes from the Yangtze cannot adequately meet the demand for their protection. Especially, those in the aspects of population ecology of Yangtze fishes, species endangerment mechanism, ecological effects of large hydraulic projects and protection strategy are not deep enough. It is recommended that scientific researches should be conducted in comprehensive survey of Yangtze fish resources, fish endangerment mechanism, techniques in artificial enhancement and release of key species, risk assessment of exotic species, ecological rehabilitation of major fisheries functional zones, etc. [ABSTRACT FROM AUTHOR]

We studied some aspects of the biology of the Zagros tooth-carp, Aphanius vladykovi, an endemic and poorly known species from Chahar-Mahall-va-Bakhtiari province in central Iran, by regular monthly collections and direct observation in aquaria over a full year. We collected individuals from Modar-Dokhtar spring of Gandoman region; we preserved some in formalin and transferred some alive to aquaria. The stomach contents consisted mostly of freshwater crustaceans, suggesting a carnivorous habit. The eggs had an average diameter of 1mm and the average absolute and relative fecundity was 415 and 110, respectively. The gonadosomatic ratio and ovary condition suggested that the reproductive season of the species was between late March and June with a peak in early April. The species is euryhaline and eurythermal and prefers neutral to basic waters. It is usually found in well-oxygenated waters, but is tolerant of hypoxia as well. [ABSTRACT FROM AUTHOR]

Gastric evacuation rate (GER) and maximum daily ration (CMAX) data for rainbow trout, Oncorhynchus mykiss are scant, particularly those that apply to field populations of this species. We determined GERs and CMAXs of rainbow trout (approx. 160--300 mm TL, 40--300 g live weight), fed chironomid larvae at 7.8, 10.0 and 12.8 deg.C. Primary GER and CMAX results are provided so they can be readily compared and combined with data from related studies. Disclosure of primary data should facilitate development of predictive equations for GER and CMAX that are applicable to the broad array of conditions under which rainbowtrout exist. Our GERs at 10 deg.C were intermediate to but differentfrom most reported in other such studies of rainbow trout at this temper ature where different food types were used. Our CMAX values for rainbow trout were substantially higher than those reported in a previous study, and we argue that our values are probably more appropriate for stream dwelling populations. We also provide evidence that Elliott's (1972, 1975) equations for predicting GER and CMAX in brown trout, Salmo trutta, should not be applied to rainbow trout as has been done in some studies. [ABSTRACT FROM AUTHOR]

We tested whether daily mortality rates (DMR) of smallmouth bass offspring were influenced by life interval, offspring density and growth, parental male attributes, and selected mortality factors during parental care in a regulated Virginia stream. Mortality averaged 9.5 % per day (range 5.2--13.9%) and 94.1% total (range 80.9--99.5%) from egg deposition to the juvenile period (29--36 d) for individual broods.Offspring losses were primarily attributed to fungus (Saprolegnia parasitica) infection of eggs and to American eel, Anguilla rostrata, predation. DMR were significantly higher for the interval from swim-upof larvae to metamorphosis relative to earlier and later intervals. There was no significant autocorrelation of DMR among life intervals for individual broods, indicating that relative mortality rates were inconsistent among broods through time. DMR were also uncorrelated with the number of offspring per brood, offspring growth rates, and parental male attributes, except during egg and embryo intervals. Daily egg mortality was negatively related to male size and positively related to the number of eggs per nest, suggesting that density-dependentegg mortality may have been partially offset in nests of larger males. Larger males received more eggs, tended to maintain larger broods throughout parental care, and contributed a high proportion of the total number of juveniles reared. [ABSTRACT FROM AUTHOR]

Predation is an important component of the life history and behaviorof many fish. In some species of teleost fishes, conspecifics respond to chemical stimuli from injured conspecifics by displaying a fright response ( such as increased cohesion of schooling. The purpose of this experiment was to investigate whether female guppies, Poecilia reticulata, display a fright response when exposed to a filtered extract made from wounded conspecifics. The schooling behavior of female guppies was observed for ten minute periods for each of three treatments: baseline treatment (no substances added to the aquarium water), sham treatment (distilled water added to the aquarium water), and alarm treatment (fish extract added to the aquarium water). Female guppies responded with a fright reaction when exposed to a filtered extractprepared from wounded conspecifics; females swam in a more cohesive school during the alarm treatment than they did in either the baseline or sham treatments. The guppy fright reaction response indicates that the fish extract is recognized by conspecifics. [ABSTRACT FROM AUTHOR]