April 9, 2014
I am planning to set-up a cardinal tetra biotope and was wondering whether trying to imitate the typical waterparameters I find in literature holds any risk in an aquarium set-up.
To be more specifc: I have always kept fish in water with hardness levels of 8 - 15 °dGH and pH values above 7.5 (usually hovering around pH 8.5). Tap water is quite hard.
Waterparameters for Paracheirodon axelrodi I find in literature are pH below 5.8 (down to 3.8) and conductivity as low as 10 µS/cm. This basically comes down to pure RO water... Good idea to imitate this or recipe for disaster? What to watch out for?
Apart from the water quality issue: what good tank mates would you suggest for a tank with dimensions 80 x 40 x 40 cm?
I was thinking about some Corydoras sp. and maybe some small cichlids.
November 3, 2008
First on the water issue, I almost have "Amazonian" water out of my tap. The GH and KH are near zero at around 7-8 ppm or less than half a degree. The pH is 7.0 out of the tap but this is achieved with sodium ash; prior to when they bagan adding this in 2001, the pH was between 5 and 6. This pH is not permanent and it lowers once the water is in the established tanks. The pH varies from tank to tank, in some it is 5 (or maybe less, the lowest test kit stops at 5), in others around 6.4 depending. I have had these parameters for 20+ years and never had issues with soft water fish.
As for the fish, generations of commercially-raised cardinals apparently adapt better to harder water, up to a point. I would still aim to keep the GH as low as possible, and the pH should naturally correspond. My wild caught cardinals are now in a tank which is well planted, and of course one needs minerals to keep the plants thriving, so I raise the GH to around 5 or 6 dGH with Equilibrium. I am not aware of this causing trouble for the cardinals. The pH in this tank is in the low to mid 6 range. I also have wild caught pencil fish, Carnegiella hatchetfish, Farlowella vittata (including fry), Characidium and corys in this tank.
Having to prepare water initially is not bad, but consider regular water changes. Rainwater can be excellent, as it will be naturally soft and acidic. Lots of wood, a part of the cardinal biotope, and dried leaves also help.
A cardinal biotope could be planted, or it could be plant-less, as they occur in both. If you intend plants, a bit of GH might be needed, depending upon the species. If on the other hand you only intend floating plants, a good comprehensive liquid fertilizer will be sufficient. Floating plants are advisable with cardinals, as they have what one writer called a light phobia. Plus the floating plants are ideal at maintaining water stability and they are ammonia sponges.
As for tankmates, you could have the Carnegiella species of hatchetfish (these are smaller and quieter than the Gasteropelecus and Thoracocharax species). Some (but certainly not all) of the pencilfish species are good; Nannostomus eques, N. unifasciatus, N. marginatus are all good. Corydoras cats are fine. These are all quiet fish in terms of their swimming activity, so a decent-sized group of whichever would be suitable. As for cichlids, this is a tank where one of the Dicrossus species would thrive (a pair) and they are very beautiful. Another suitable fish that comes to mind is Farlowella vittata.
April 9, 2014
Thanks for the clear info Byron! I envy you for having 'Amazon water' coming out of the tap, this is something I can only dream of.
I will probably resort to buying RO water as I don't trust my rainwater: combination of air pollution and zinc coated gutters will not be very beneficial for my aquarium.
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