Are guinea pigs aggressive? Not usually; however, if provoked he will defend himself. Guinea pigs are typically gentle creatures that like to live in community. However, there are times when they can become aggressive. Signs of aggressive behavior may include lashing out, biting out, or even hissing. Some guinea pigs show signs of aggression because they are lonely, scared, or simply because they’re new to your home and environment. Some guinea pigs will show aggression towards each other when it comes to food or fighting over who gets the girl. It’s recommended that you have a guinea pig pair, but make sure you don’t have two males and ensure the two females are getting along. If there’s an issue, separate the guinea pigs. Do not allow children to feed or hold the guinea pig if he’s aggressive. Call your vet Crown Point, IN for h elp.