The best way to tell them apart is the anal fin or caudal fin, cant remember what it is called exactly... It is a very noticeable difference. The female will have a normal fin and the male will have a a spiky looking fin that he usually holds against his body. In order to see these I suggest finding a dull looking guppy(probably a female) and looking for the normal fin and then finding a fancy looking guppy (most likely a male...) and spotting the difference between the two.
|