taking care of guppies

Question
I have a ten gallon fish tank with guppies. I was wondering how many you are to have in a ten gallon tank and what happens if you have to many. I was also wondering what temperature the water needs to be and how often you need to clean the tank. Also, how do you keep the fish from reproducing so fast. I had two fish in the beginning of September and now in the beginning of March we have over 30, what am I to do? I don't want to kill them. We are also wondering if you need to have the light on all the time and if you can unplug the thermometer in the middle of the summer. It would help if you could tell me all the aspects of taking care of guppies.
      -THANKS VERY MUCH!!

Answer
Hi Linae
Well, using the general rule of 1 inch of adult size fish per gallon(only applies to community/tropical fish), I'd say you could comfortably fit 5 guppies in a 10 gallon, I'd go no more then 7 though.  If you have too many fish in a tank, or the tank is too small for a fish, you run into several problems.  One of which is the fish can/will end up stunted.  Basically what happens, there's a hormone that tells the fish to stop growing on the outside, but it's insides/guts keep growing.  This obviously isn't good for the fish at all.  Another problem is the water quality suffers.  The ammonia, nitrite, and nitrate levels rise and this stresses or kills the fish directly or indirectly through diseases/parasites.  

Guppies can actual survive in a wide temperature range, about 68F-82F + .  I keep my tropicals/community fish at about 78F.  As far as slowing down their breeding, I really don't know if that's possible to do.  You could try slowly lowering the temperature in the tank, see if that helps.  

Your best bet, is to get another tank, and separate the males and females.  But, females can store sperm in them, and can still have babies with no male in the tank for several months.  You should try to locate a mom and pop pet store-one not chain owned, and see if they'll take some of the guppies.  They may give you store credit for them, though not much.  But being as guppies are such prolific breeders, it will probably be hard to find someone who'll take them-and won't use them as feeders.  

As for the light, don't leave it on more then 8 hours a day.  Otherwise you'll end up with algae problems.  Yes, that's fine to unplug the heater.  Especially since they can handle a wide temperature range.  The main thing is you don't want swift major temperature changes, that's what shocks/kills the fish.  I usually unplug all my heaters for the summer time, I usually keep my house temp higher around 78-80 F.  As for the tank cleaning, for a "normal" tank that isn't overstocked and has adequate filtration, I usually recommend doing a weekly water change of about 25%.  But in your case, your tank is way overstocked with 30 of them.  I'd recommend doing a water change every 3 days of about 30%, and be sure to do a good and thorough gravel vacuum also.  Really consider either another tank to separate the genders, or get rid of most of them.  They'll overrun you so quick, as you're finding out.  

Hope that helps, and Good luck!!

Christy