Guppy Pregnant

My guppy is really big and want to now if he or she is pregnant, how can you tell between a boy/girl?

here is a picture (sorry for being bleared hard catching fish):





it has been like this for at least 3 weeks. if pregnant when should i put it in a breading box and when the fry are hatched should i move it to a really small tank with no filter or heater and take a bit of water from the tank and keep changing it every day??

The pictures are really too blury to tell anything by, if you could try to get some better ones we'd probably be able to offer a bit more help. Heres a diagram of male/female platy comparisson, but you sex guppys the same way it's not the best but it'll help you to identify wheter it's a male or female. http/sogua.mamakcorner.com/uploads/Platy_sexing.jpg
If she is a female, then you will only be able to tell if she is pregnant or not bye the black/grayish Gravid spot.

"when should i put it in a breading box" Watch her gravid spot over time, it'll start to get bigger and darker, you wont want to put her into the breeding box untill just before she's about to give birth(We can help you more with this once we know for sure she is a girl)

"when the fry are hatched should i move it to a really small tank with no filter or heater and take a bit of water from the tank and keep changing it every day??" Guppy are livebearers, that means that they give birth to live young like humans or dogs. They don't lay eggs.

I ignore gravid spots completely since they have been fooling me for over 50 years. Instead I go by shape for a near term livebearer. When you see a squaring off, the female is getting close to a drop. To determine the sex of a common livebearer, a poeciliid, like a guppy, I have real fish pictures here that you can use to compare males and females. The thread is located here and yes, it is one I put together. I also have a link to it in my signature area.