I am going to re-itterate what everyone else has said...NO MORE FISH in that bowl!
Just about everyone here that has answered your post is extremely knowledgable and to not take their advice is crazy! :duh:
Yes paradise fish can be kept in STABLE lower temps, but not lower than 68-70 F is what I would reccommend.
Also, majority of these fish are bred here in the states where breeders use filters and heaters to keep their tanks constant and are not wild caught - if they were wild caught, then maybe they would be a little more tolerant of lower temps, but good chances are that they're commercially bred and are not used to lower temps like that....especially such a large temp fluctuation as you have going on.
Just do your fish a favour and invest in a 5 or 10 gallon tank from walmart or something - heck from anywhere - and add a heater and filter please...surely if you can accomodate a large 180 gallon, then a small 5 or 10 should be no problem.
I agree with everything that the others have said here, and it would be wise to follow the advice given....think of your fish....