Ιδανικες συνθηκες για:
Neon Tetras
pH: 5-6
GH: 0-1
T: 24-29C
Cardinal Tetras
pH: 3.8 - 4.8
GH: 0
T: 23.5 - 28.5C
Πηγη: The history of the neon and cardinal tetras by Heiko Bleher
http://www.hagen.com/pdf/aquatic/Nutrafin_Aquatic_Ne.ws_USA.pdf
σελ
....The species (neon tetras) is found primarily in Peru, in the so-called quebradas, small clearwater streams with a significant blackwater component, where the pH varies between 5.0 and 6.0 and the temperature between 75 and 84°F, and the total hardness is less than 1.0°dGH...
σελ 5
...When such sensitive fishes (cardinal tetras), originating from extreme water conditions where the pH fluctuates between 3.8 and 4.8 and the temperature between 74.5 and 83.5 °F, and where the total hardness is so small as to be virtually unmeasurable..
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Οσμωτικη λειτουργια του Neon tetras
Ionoregulatory specializations for exceptional tolerance of ion-poor, acidic waters in the neon tetra (Paracheirodon innesi).
Gonzalez RJ, Preest MR.
Department of Biology, University of San Diego, 5998 Alcalα Park, San Diego, California 92110.
gonzalez@acusd.edu
Abstract
To better understand how fish are able to inhabit dilute waters of low pH, we examined ionoregulation in exceptionally acid-tolerant neon tetras (Paracheirodon innesi), which are native to the ion-poor, acidic Rio Negro, Amazon. Overall ion balance was unaffected by 2-wk exposure to pH 4.0 and 3.5.
Measurements of unidirectional Na+ fluxes during exposure to pH 3.5 showed that tetras experienced only a mild, ionic disturbance of short duration (</=24 h) as a result of a stimulation of Na+ efflux.
At pH 3.25, Na+ efflux was almost fourfold greater (all fish died within 6-8 h). At both pHs, active Na+ uptake was not inhibited, and in fact, at pH 3.5, uptake was stimulated. Kinetic analysis of Na+ uptake at pH 6.5 and 3.5 produced virtually identical low Km values and high maximum-transport values.
These results confirmed the pH insensitivity of the uptake mechanism and revealed a mechanism well designed to operate in the dilute, acidic waters of the Rio Negro. Na+ influx was only mildly sensitive to amiloride (a Na+ channel blocker), which, along with the pH insensitivity, suggests that Na+ uptake may occur by a novel mechanism. Na+ efflux was reduced by addition of Ca2+ to the test water at pH 6.5, but the effect disappeared at pH 3.5.
Exposure to LaCl3 (a strong Ca2+ displacer) also stimulated Na+ efflux. These results suggest that Ca2+ plays a role in determining branchial ion permeability at high pH but that, at low pH, where Na+ efflux is stimulated, alternate, Ca2+-independent mechanisms are employed to control Na+ efflux.