The population density of perch, Perca fluviatilis L. in the Cikola backwater system of the river Danube, Hungary
The numbers of perch Perca fluviatilis in the Cikola backwater system of the river Danube were estimated by mark-recapture techniques using multiple fishings. Fish were caught by fyke nets and electrical fishing. The latter method was unselective for sex and the catch data could be used to correct the sex bias in the fyke net catches. A population estimate in April of 6059 ind ha−1 (95% C.L. 5135–7386) for perch > 5 cm was obtained for a 0.6 ha area of backwater and 1665 ind ha−1 (95% C.L. 1204–2692) in May for a 0.4 ha area of a small bay.
Environmental Enrichment and its effects on Welfare in fish
Although public and consumer awareness is increasing fast in regard to welfare in captive fish; one often neglected aspect of fish welfare is the complexity of their holding environment. Increasing the complexity in any given way is termed environmental enrichment. Enriching the environment of fishes can have various positive effects on physiology, health, survival and therefore general welfare. However, it usually is also increasing labor through increasing maintenance and handling time and is lowering thus the efficiency. Fish welfare in general includes also the acceptance that fish can feel a certain degree of pain and should be considered, at least to a certain degree, sentient and conscious beings, which is scientifically still under serious debate. 
Under the assumption that fish have the capabilities to feel pain and are, at least to a certain extent, conscious and sentient beings, the often neglected welfare‐aspect of environmental enrichment and its effects on fish under captive conditions are discussed in this review. This includes farmed fish for human consumption and restocking purposes (aquaculture) and fish kept for research. A definition of environmental enrichment is as well provided as a historical context, different enrichment types and the aims of environmental enrichment and areas of its application. Whether or not fish can feel pain is also debated. 
An extensive table is included, providing natural micro‐, meso‐ and macrohabitat preferences of some important freshwater salmonids (rainbow and brown trout, Arctic char), Eurasian perch and common carp in different life stages (fry, juveniles, adults). Furthermore the environmental enrichment is considered under the perspective of in‐stream restorations and its effect on, primarily, salmonids in culture. Environmental enrichment includes physical structures added to the captive environment to provide increase the structural complexity while other forms of environmental enrichment may include sensory, social, nutritional or even occupational enrichment. The latter, however, is usually not of higher importance for fish. In the various research papers reviewed, it is obvious that environmental enrichment can provide several beneficial advantages although some negative effects have been observed too. Observations of environmental enrichment effects on a production or farm level are basically completely missing in the literature and therefore a large knowledge gap exists between laboratory studies and practical application. While several types of environmental enrichment have been adapted to aquaculture out of necessity, mainly in terms of reproduction success, little is known of environmental enrichment effects on fish welfare under production conditions and whether benefits may outweigh the drawbacks like increased installation costs or increased effort for maintenance.
Neuronal uptake inhibitors, nisoxetine and fluoxetine on rat vascular contractions.
The importance of neuronal uptake processes in rat arteries and veins was compared using nisoxetine and fluoxetine, selective inhibitors for neuronal uptake of norepinephrine and serotonin, respectively. Nisoxetine (10(-7) - 10(-5) M) increased the sensitivity to exogenous norepinephrine in the portal and mesenteric veins (10-fold) and in the mesenteric artery (2.5-fold). Responses to field stimulation were also increased afternisoxetine in all three vessels. After nisoxetine, aortic responses to norepinephrine were unaltered and in all tissues, serotonin-induced contractions were reduced. Fluoxetine did not potentiate responses to norepinephrine or to field stimulation except in the mesenteric vein where sensitivity to norepinephrine was increased and the relaxation rate after field stimulation was prolonged. Although serotonin has been detected in blood vessels, fluoxetine did not increase vascular responses to serotonin. These studies suggest that rat mesenteric veins have a highly sensitive neuronal uptake mechanism of norepinephrine. Furthermore, these data provide indirect evidence against a functionally important serotonergic uptake process in rat blood vessels and suggest that neuronal uptake of serotonin does not exert a major role in terminating the vascular action of this biogenic amine.