The male managuense's they tend to have more of a protruding mouth and slender like shape like yours,and the females tend to have more of a roundish shape.Try comparing pictures of males and females and you will see the difference
i did have a stunning breeding pair, at 10" but i sold them because they were in a 40 g for 2 months ever since i took them out of my 180g, and i am not upgrading soon unless i find a 48x18x24 tank stacked on a medal stand with a 55 g right under it cuz right now i have a 40g stacked on a metal stand with a 30 g under also pic shows a female , male, and then the female in different colors, most the time males have more deep colors on the bellys while females usually dont have a dark pattern on the belly but they can sometimes.