Re: [RML] Melanotaenia trifasciata

peter.unmack at ASU.Edu
Fri, 13 Aug 1999 17:42:29 -0700 (MST)

On Fri, 13 Aug 1999, Bruce Hansen wrote:

> > For most Australian species specific water conditions are not
> > critical as over the course of a year conditions at any given location can
> > change radically from very soft and acidic (from tanins, not fish poo) to
> > harder and alkaline.
>
> I'm not aware of any surveys of Cape York streams in the wet season that
> confirm that they change from soft and acid to become hard and alkaline with
> the addition of lots of rainwater (which is usually slightly acid and soft).
> So my prediction is that they change from soft and very acid to soft and
> less acid.

You're right, I don't have the physiochemical data, although I'm sure we could
both find data to back up our ideas. My main point was that many people fall
into the trap with Australian fishes of paying too much attention to whether
their fish are at 20 or 200ppm. For _most_ of them it doesn't make any
difference at all.

> Of all the Trifasciatas that I have collected and kept over the years
> Michael, only Goyders seem to need pH over 7.

To survive or breed? Does anyone have any accurate data on the lower pH
limits that rainbowfish will successfully spawn and develop at? I certainly
know folks who have had rainbows not reproducing, checked their pH, found it
acidic, raised it and gotten eggs shortly after. Unfortunately few people
keep good enough records to really know for sure.

Tootles
Peter Unmack