I have a male betta that I have had for almost 2 years. He is currently in a 5 gallon tank. He used to share the tank with another betta (had a divider) for about over a year and a half. He now has the whole tank to himself. About a month I bought a "baby" betta from PetCo. I'm guessing the age is about 2 - 4 months old. I am 99.9% sure it is a female. She has a white spec on her belly which I am assuming is her egg spot. She also does not have very long fins. My question is can I put her with my male or would that be a bad idea? There are a lot of plants and there is a "cave" type decoration that I don't think the male can fit in to.
Yeah, your best bet would be to divide the tank. Otherwise the two will almost certainly attack each other just like two males would, resulting in injury or death. With a secure divider there's very little chance that they'll bother each other, especially if they have enough plants & hiding places so they're not in each others sight all the time.