Hiya i'm new to tropical fish and have got my first tank it's a 150 litre we have about 35 fish ie: gourami's tetra's cicklids mollies,platy's. We have noticed that the female platy's are getting very fat, at the bottom of the anal fins they are going dark and can see black like eye's, but im not 100% sure if they are pregnant or not or what stage there are into there pregnancy? I do have pictures that i will try and post for people that can help me.