Coldwater Livebearers..

[Ludwig Venter]

on 21st June, we'll be slap bang in the middel of winter here in S.A., so obviously, I have some potent (4kw geyser elements) in my outside ponds to try maintain a water temp around the 26 deg C margin......

The past 3 days, I noticed that the fish are'nt eating as vigorously as usual, so decided today that maybe a good water change is necessary.... When I put my hand in the water to submerge the syphoning hose........Ice cold.

The guppy pond was 10deg C and the platy, molly and swordtail ponds were all at 12 degrees...... On checking, the outside plugs tripped on the main switchboard...(probably overload with 4 x 4kw heaters connected to one plug)

The fish were all fine considering that we've been having fluctuations between 6 and 22deg C day temperatures since Monday. The guppies and Platies seemed the least (if at all) affected by the colder water. The swords and particularly the Mollies was sluggish and slow moving, but all survived.

I wonder if the fact that they are of many generations, (at least 10 years) year round outside stock, has evalutionised them to acclimatise to the elements....

 

[saltynay]

10 years stock means around 60 generations if this temperature variance has been happening for that long then I think you may have the start of a hardier species being developed as only the strongest would be kept in the genetic pool. Guppies are hardy anyway they can be kept around 14C but will not breed at these temperatures.

 

[Gill]

Cool, looks like they have become hardier with more generations of the fish

 

[helterskelter]

i take guppies down to 16 most winters to give them a rest and that not a problem.
Although i did kill a load when i left them out to long and a early frost killed them off

10 is very low. However if the temp change is very slow then they may be able to cope, just dont wack the heaters on full blast just yet, do it slow to allow then to get use to it.

 

[Ludwig Venter]

i take guppies down to 16 most winters to give them a rest and that not a problem.
Although i did kill a load when i left them out to long and a early frost killed them off

10 is very low. However if the temp change is very slow then they may be able to cope, just dont wack the heaters on full blast just yet, do it slow to allow then to get use to it.

I am now contemplating a little experiment here....... It'll make a huge difference to my electricity bill if it works.....

 

[helterskelter]

should keep a log of the water temps in an unheated pond.
but if the water drop's any lower you will lose some fish.

Swords from the wild live in cold mountain streams and often find a frost on the land so you could look at some of the wild swords if u can import them.