Obviously there really can't be one single food that would be nutritious and delicious for every single pet out there! Not only do certain animals require certain nutrients and vitamins and food consistencies, but a lot of individual pets can be picky about what they will or won't eat! My uncle's dog, for example, used to eat his breakfast if and only if it was dry white toast cut into 6 pieces. (I wish I were joking, he was impossible to please with anything else!) And obviously the amount of food that would satisfy an angelfish wouldn't come close to filling the mouth of a horse. Every animal is different! Although there are some foods that many of them all like, such as carrots -- my dogs, hamster, horses, birds, and even ferrets have all loved carrots --there is no one food that's good for all of them!