ok everyone, we were all new too. lets try and be cool about this...

   guppity, do you have a filter? a heater? a tank thermometer? how LONG did you cycle your tank? 1 week? 2 weeks? more?

   and, by what STRAIN, US meant, what BREED are you guppies? if you haven't got a clue, what color is your male? what patterns does he have and where are the patterns on his body?

   a fry is, basically, a baby fish. although guppies DO start out as eggs, the egss hatch INSIDE the mothers body. then, the mother gives birth to live fry.

   you said your females got the gravid spot on day 2, near their gills? the gravid spot should NOT be near their gills. it should be right above the anal fin. don't know what that is? it is the fin right next to where the poop comes out. the gravid spot really just means that the guppy is a FEMALE, not pregnant. all females have one, at a very early age. the gravid spot gets larger/darker during a pregnancy because it is the fry's EYES that are developing, while the fry are still in the egg sac.

   like US asked before, were these females kept with the females at the store? iun the same tank?

However, if you're getting a second tank for the fry, then basically suit yourself with the gravel.  Fry are generally smart enough to not go burrowing in any sort of gravel, and if they do, it generally means they're dying anyway.  So feel free to put some in.

I would suggest buying the second tank, if that is what you are referring to, as soon as possible so the water can get cycling before you put any new fish in it.  Try using some of the gravel from your current tank, and when you fill the "nursery," use about half of the water in your 2.5 gallon to start with.  I'm worried that you might not have cycled the 2.5 gallon, but if you're off the hook and the fish are fine, make sure you don't take the same chance with the guppy babies.

A good rule of thumb to remember is that each guppy fry should be allowed the one gallon that its adult self will be allowed to grow in.  That means if your guppies each drop ten fry, you'll need about ten gallons per pregnant female once her offspring all grow up, assuming they survive.  You see why guppy-rearing is a rapidly expanding hobby?

The same goes for your 2.5 gallon.  Each of those fish should technically have a gallon, and remember that the 2.5 measurement is before any substrate, decorations, or plants are added.  As long as you keep up with the water changes, you might be able to keep up with it.

I also have crammed a trio of new guppies into a 2.5-gallon aquarium, until I could get them bigger quarters. Would you please go to the Google search engine within Guppylog and search for tank size?

I really want to applaud you for asking what you should do about fry BEFORE they arrived. More of us need to do that when beginning (or continuing) the hobby. :)

In Immediate Help and, as soon as time permits, please read through the sections on

New Tank/Cycling/Setting Up/Water Changing
Breedings
Pregnancy and Birth
Fry Diet and Safety

It is important for you to be familiar with what cycling an aquarium is. Where is you tank in that process? Many fish are great after a week, but not quite as tip-top later if the tank is not under control chemically. And small aquariums are particularly vulnerable to problems.

Why do you think your females have been pregnant since the second day you have had them? More to the point, were they kept with males before you purchased them. :)

Dechlorinators do not sterilize the water. They remove the sterilizing chlorine (which kills foreign life including guppies.) Does your tap water have chlorine or chlorine and ammonia (=chloramine)? Knowing that will determine if you need a dechlorinator and which type of water conditioner you should use and that also is a matter of life and death.

Tomorrow is Sunday and you may only be able to ask your pet shop or neighbors what your water department puts in the water. If you are an American, you should be able to call up your municipal water department (if you have one) and ask for the periodic report they are supposed to send to the EPA and make available to citizens. (One of those "your tax dollars at work" sort of thing.)

If they put in chloramine and you just treat for chlorine, that can be serious trouble when the dechlorinator releases a big ammonia surge. Also, have you accumulated a couple water jugs (gallon?) in which you can season treated water for a week before adding it to a tank? (See seasoning water.)

That may sound unfair to ask of a new aquarist, But why not start off right? It doesn't seem fair to tell people these things only after a month or three.

Gravel is somewhat unusual in a small tank, but it can be a help as and after the tank is cycled. Do you have a friend who has a healthy aquarium and could help you seed your tank (with beneficial bacteria) by giving you a couple of handfuls of gravel (put in a bag and taken home to your tank wet). I wouldn't get that gravel from a petshop, unless conditions become really desperate, because so many diseases flow through ships with the fish.

The plain, small plastic birthing boxes (a serious racket) are sometimes called the Plastic Box 'o Death. You may have referred to a larger plastic box and that might change the conversation if it is a five or seven gallon sweater box. Check out the thread pretty much by that name under Breeding in Immediate Help. If you want a rant on that, search for plastic breeding boxes with that Google thing.

I purposely haven't directly answered your questions and several implied questions. But if you answer mine, you will be on the way to answering several of them and we may be better able to respond to you in the future.

And your guppies will thank you. :)