From previous Post:
First, regarding sex recognition, the guppys are very easy to recognize: Males, usually smaller and more colorful, have a copulatory organ on their underside, called gonopodium, which is actually a modified anal fin, whereas females have their anal fin cleanly spread in triangular shape (it can be collapsed at will, but is usually clearly visible). Bear in mind that fertilization in these fish is internal, and the fry are alive at birth, not eggs (they are viviparous).
Second, regarding pregnancy: Their cycle is +/- 35 days, and they do develop a distinctive black spot ventrally, in front of their anal fin during this period. Towards maturity, the underbelly of the female looks almost square, as the fry are already formed "lumps", still inside. I've had females give birth to as many as 16 fry, but those where fairly large females (3 to 4 cm).
Third, regarding birth: The first time I (involuntarily, like you) bred guppys, I placed the pregnant female in a 1 gallon Mayonaise jar, filed with water from her original tank, and with big marbles on the bottom, and some floating plants. I had to wait almost 4 days, as I was to early in separating the fish, but better safe than sorry... In any case, as the fry are first expulsed into the water, they are somewhat deformed from their cramped previous habitat, and are not great swimmers. They will either float to the top, where they can hide in the floating plants, or, more often, sink to the bottom, where they will fall between the marbles to safety. Following this, I replaced the female in the original tank, and saw the fry stretch and begin active swimming almost the same day. Depending on the size of the other fish in your main tank, fry could be put in the main tank rather quickly. In my case, I waited 10 days. I don't know wether this is too fast or too slow on average, but it worked well in my case.
I hope your fish is not sick, but pregnanat, as the latter is a much more appealing alternative
) Anyways, how big are they? I put mine in a week early. Trust me, they are huge when they are about to drop. They also shoudl look for a place to hide, and shoudl have not shown any interst in food. They should be fairly territorial about teh place that they've chosen to hide. The bottom of their sto,achs should be flat also. Don't get too stressed over it. It will happen, and if it doesn't work out, she'll have tons more, too much that you can handle. Good Luck!
