Re: [RML] Connieae & Furcatus

Mach T. Fukada (fukada at hawaii.edu)
Thu, 16 Apr 1998 01:11:54 -1000

>I have found that P.mellis are particularly photoperiodic in their breeding
>and by controlling their day-night cycle to about 14 hr light/10 hr dark and
>keeping them well fed you can increase their egg productivity.
>
>If the tank is in a room that must be used during the "night", cover it with
>a black plastic drape to keep out ambient light and provide a separate tank
>light, inside the drape, that is controlled by an automatic timer.
>
>However, it hasn't seem to work with the popondettas. I still thing it was a
>change in barometric pressure and they probably think it is the beginning of
>the wet season particularly seeing that we haven't had a wet season over
>here this year. Temperature and photoperiod no doubt also has some effects.
>Maybe it just a matter of getting all of them in sequence. In the wild there
>is usually a drop in temperature at the beginning of the 'wet' plus an
>increase in daylength. What we need to do is get all the weather readings
>for their breeding time in the wild.
>
Adrian,
I have wondered about this also. I also figured that high concentration
of minerals and tanins and other organic acids might simmulate the dry
season. Then as the rains return tanin etc. levels drop dramatically and
trigger changes and stimulate egg production and breeding. hmmm PhD
disertation here. Or looking at the fact that many of the Pseudomugil eggs
can be forced and appear to be able to lay dormant in peat and other
organic/acid substrates. Maybe increase in tanins is the trigger to start
breeding. Then eggs laid that survive the dry season to hatch out as the
rainy season uncovers them or disturbs them like the forcing technique.
D. Onishi and Chuck seemed to feel that temperature was more important for
mellis in Hawaii as we don't have much of a change in daylength and
breeding appeared only in the spring. Also seemed like the more temprate
populations of mellis needed more cold. But adjusting the daylength was
never mentioned here to me. It might be something for them to try.

MTF

Mach T. Fukada, Web Master
fukada at hawaii.edu
Honolulu Aquarium Society
http://www.geocities.com/Heartland/Meadows/2948/HASF.html