

David can you see the big difference in the length of these female's dark belly areas. Now most of these are carrying eggs, some more than others which pushes that area up more. But even without being this full of eggs, the females dark belly area does not extend down as far as the males. It's easier to tell male from female in the light colored plecos using this method. With the browns, it's better to get a look from the top down at the shape of the sides. Males are tapered through the sides much more. On the browns, unless you're looking in person it's hard to tell from a pic exactly where the dark area ends.