platy and 2 guppies, are they pregnant?

Question
i have had my tank for 1 year it is 10g i have 2 female guppies 1 male guppy 1 female platy 1 male platy, 2 baby female platies 3 months old, and a couple small snails that hitchhiked on a live plant i got from aquarium depot in randallstown, my filter is a  bio aqua filter the one that hangs over the edge and has a tube going down into the water pH is 6.7 ammonia is 0 nitrite is unknown i change the water every 4 weeks 5 gallons are replaced each time... now the problem i have is a 2 part problem, i have 2 female guppies that are not fat but have black dots in front of the anal fin where the waste comes out, are they pregnant even though they're not fat? because within today i found 2 babies and put them into a breeder net along with a fake plant and the 2 guppies. the other problem is that i have a platy and shes really fat but there are no black dots their is only red dots in the butt, is she pregnant? please help me!!!

Answer
Hi Jake;

Since you have males in there you will probably have babies in few weeks. It can be really hard to tell for sure when they are "due" though. Usually the pregnant female will hide more when she is 4 days or so from delivery. The "gravid spot" near the anal fin is where you will see the eyes of the babies as they develop. If the babies have black eyes, the gravid spot has darker dots. If the babies eyes are red or light in color, so are the dots.

Guppies and platies need very clean water for good growth and vitality. Your tank needs a 25% water change once a week to keep it clean and healthy. They can have babies about every 4 to 6 weeks. Provide plenty of places for the babies to hide and crumble up some fish food really tiny for the babies starting a day or so after they are finally born. They only need a little bit of food but they really should eat 3 to 5 times a day.

Good luck!

At Your Service;
Chris Robbins