The most popular and beginner-friendly option for a pet is the fancy mouse. When choosing your new pet, it is highly recommended to buy from a reputable, ethical breeder instead of a standard corporate pet store, as breeder mice are typically socialized early and bred for better health, longevity, and a calmer, friendlier temperament. When picking out your mouse, look for one that is active, alert, and has bright eyes and a smooth coat, with no signs of respiratory issues like sneezing or wheezing.