Pregnant fish behavior

Question
My fish had babies.  I'm afraid that it might be pregnant again.  What kind of behavior does a pregnant fish have?  How can I tell if it is pregnant again?  I had no idea the first time they had babies.  I just came home one day and was about to feed them and noticed a bunch of little fish swimming at the bottom of the tank.  I don't have a very big tank so this situation has me a little worried.

Answer
Well live bearing fish have (on the female) near the end of their body where it meets the tail fin a black dot or cavity. This is where the young fish are kept until birth. You can tell if she is pregnant by a vivid black dot. What kind of fish is yours? I need to know in order to answer your question.