[Killietalk] Choose your temperature

[LeeH920226 at aol_com]

I have been experimenting with a pair of Aphyosemion cyanostictum that have 
been laying eggs off and on for several months. Last summer, when the air 
temperature in my basement fish room was 80 degrees, The water temperature in their 
tank was 75 degrees. They produced no eggs. Then I moved them to a cooler 
area in my workshop where the water temperature went from 75 down to 68 degrees 
F. They started laying eggs fairly consistently. This Fall I moved them back 
into the basement and started with the tank on the floor and they continued to 
lay eggs until recently. So I checked their tank water temperature and found it 
to be 62 degrees. A few days ago I moved their tank to a position a few feet 
off the floor. Today I was rewarded with a few eggs. So I did some temperature 
measurements of different heights on a wire shelf on wheels on which I keep 
various fish in 2.5 gallon plastic tanks. These are the temperatures recorded:

Distance off floor  Temperature
0 feet              60 ºF
1 feet              62 ºF
2 feet              64 ºF
3 feet              67 ºF (where the cyanostictum are)
4 feet              68 ºF
5 feet              70 ºF

     It is obvious that these fish like it cool, but not too cool. With the 
change of seasons, I need to just keep moving them until I find 67-69 degrees.
    On the other hand, I have a group of Austrolebias alexandri that, for the 
third winter now, are actively spawning in an unheated area where the water 
temperature today was 40 degrees F. I have never seen fish that are more active 
as the temperature gets colder. In the summer they lie around listless.

Lee Harper
Media, PA

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