Do I need to disclose prior mold issues with a house I'm trying to sell?

[Ana Hyler]

I'm wanting to purchase a house with mold issues and erradicate the mold myself (pro's ask way to much) ! I want to flip this property, but I'm afraid that if I disclose prior mold issues and I say I cleaned it myself, they would be afraid and I might loose potential buyers. Do you know if this is something I HAVE to disclose? I mean by the time I put it for sale, the mold issue should be long gone.