Here is the problem: when even the two guppy males are added, they knocked the whole equilibrium out of whack. The ammonia increased, owing to their metabolism. In time, that bubble will go through the process. You didn't mention what the nitrite readings might be. The nitrate reading can be a bit of a problem at that level and wouldn't be hurt by a water change.

Larger tanks are a little less vulnerable to the problems you mention. Smaller tanks can have some pretty extreme chemistry jumps in just a little time.

If you can, look for those.

Now here is the quick fix: change two gallons of water either with treated tap water of about the same temperature or even two gallons of commercially produced drinking water. Around here the generic stuff is ranging from 59 cents to 99 cents for a gallon bottle.

After you have removed two gallons of tank water, gradually add the new water. I use a piece of appropriately sized airline tubing (or a length of hard airline tubing out of the jug and soft silicone airline into the tan.). That gradual change is a little less stressful. Having the changing water as warm as the tank is also a stress remover.

There are at least two other things, which will help. One, if you can, turn up the filter or add an airstone. Two, if you have you have a gravel vacuum, use that to get some of the gunk out of the gravel since that will remove some of the organic load which the tank must deal with. (Poop happens.)

Water changes will slow down the development of a new equilibrium, but a more gradual process will be less stressful on the fish. Less stress is always good. :)

If things still are not looking good (the guppies are having trouble breathing and getting enough oxygen) there are two more drastic things you might do. One, dose the tank with your water conditioner if it breaks down chlorine and (more importantly) temporarily bonds some of the ammonia. This again will slow down the re-establishment of the nitrogen cycle in equilibrium. But you will still have fish to establish that equilibrium. ;)

Two, take an eye dropper and add no more than 5 drops of hydrogen peroxide to the filter so it is spread around the tank. Adding more than that will burn the fish's gills.

What about those two 1-gallon water jugs? When all of the above is done, fill them with cool tap water (less metals than in warm water) and treat each jug with your water conditioner. Let them sit, with the tops off, three days and then consider another partial water change. (And of course refill the jugs...)

Seeing lethargic fish and doing a 25-45% water change seems like a pretty simplistic solution. However it is amazing how often that extra water change (or series of partial water changes) will give your tank and fish the boost they need.

Please let us know if the water changes help. If you already have some water sitting and seasoning, obviously you don't need to dash out and purchase the drinking water.

By the way, it might make no difference, but a small submersible heater, set at about 77 degrees F. would smooth out that temperature fluctuation. We're spending a lot of your money here. Is there a birthday coming up soon? How about a deal with Santa or Mrs. Santa for an early stocking? (If you are as greedy as me, borrow and use pantyhose.)

I have dropped several terms here associated with establishing and re-establishing an ammonia cycle equilibrium. Even if you are familiar with all of this "aquatic Latin," please, when you find time, click on the Immediate Help link in the upper right hand corner of these pages. (And they are still not just for newbies!) I think if you survey that section on setting up new tanks and all that, you will find some nuggets of info which will be useful for you.

"Like everyone else, owing to the inflexible architecture of this site, you misunderstood the instructions (like 99% of us) and submitted this as a log. However a log is a multi-page dissertation of something in the hobby or a very complex question. I voted for your entry - this is your "Mulligan" - because I hope this is retained on the front pages of GL long enough for you to get started. :)

Your post is more of a short diary - which will usually get responded to more quickly anyway in that section. In the case of an emergency, that is definitely the route to go. So too use diaries for short takes of a few lines. Cruise several diaries and you will see what I mean."

I think our biggest diary here was somewhere between a mere (!) 1,000-1,500 words. ;)