Please send a picture of the bottom of the leaf. Do you see small black specks that may indicate infection? Sap sucking insects may also be the cause, look carefully underneath the leaves and at the soil surface. Make sure you water once the soil is dry, then saturate it until the water runs out. This site has a plethora of information on Mango's and their native habitats. Try to mimic it's native growing conditions in your home. https://www.hort.purdue.edu/newcrop/m...