Feeding your ferret is an easy thing to do, but should be done with consideration to his natural diet and how he digests foods. Ferrets are carnivores and must have a diet that is composed primarily of meat. This isn't as hard as it sounds, but it is indeed important. While people can be vegetarian or vegan and have a healthy lifestyle, ferrets cannot. With a little bit of knowledge, you can have a healthy and happy ferret.
Pellet food. The best option for your ferret is a dry food similar to cat biscuits or kibble. You don't want to feed your ferret dog food because it isn't nutritionally balanced for a ferret. However, you can find good quality ferret pellets and premium cat food that is balanced well for a ferret. Many ferrets become finicky eaters and would rather starve then try something new, so it is often a good idea to give your ferret a mix of three or more types of food in case one might not be available in the future. This way, if he is used to several types, then he will still have food options should something no longer be available.
Your food should be about 30-40% protein and 20-25% fat. It should be low in sugar and fiber. Most high quality cat foods will follow this as well as most ferret foods. You will also want to check and make sure that meat, meat meal, poultry, and/or eggs are somewhere near the top of the ingredients list. Proteins from plant materials such as soy and corn aren't good for your ferret. Ferrets also tend not to like fish and will often not eat food that is made from a lot of it. It is also a good idea to ask what the ferret has been eating before you acquired it. It is a good idea to switch your ferret slowly to try and get it adapted to a new healthier diet. This is especially true if your ferret is older and eating a very poor diet.
The food dish. Most ferrets are diggers and love digging through a big dish of food which can lead to messes and isn't good for the ferret. To stop this, it is good to hang food dishes from the side of the cage and to stick with a smaller dish rather than a huge one. If you have more than one ferret, then it is a good idea to have more than one small dish so there is enough food available for all of your ferrets without having the digging issues. You should feed your ferret about 1/4 to 1/2 cup of food at a time, per ferret. The dish can remain in the cage at all times. If they finish it quickly, avoid filling it up over and over again, but it is definitely okay for them to have the food available if they don't finish it.
Water. Water is important for all animals, and especially ferrets fed a dry food. While the dry food is good for their teeth and doesn't go bad (as moist foods or fresh meat does), it doesn't provide moisture. It is a good idea to provide a shallow dish of water that your ferrets can drink from and play in, but you should also have a large water bottle so that water is always available and your ferrets never go without.
Treats. Ferrets are like little kids wrapped in fur (that tend to be quieter and happier!). They love treats and there are a variety of options in giving treats to them. All treats should be given in moderation. It is best to give them ferret treats that are similar to their diet and meat based. However, the occasional human treat can be given if you choose the right option, such as hard boiled or scrambled eggs or small bits of meat. Some people also give bananas, raisins, dried fruits, lettuce, Cheerios, bagels, and other low sugar bread products.
It must be noted, however, that fiber and sugar are bad for the ferret. Lots of treats can cause a number of issues and you can make it so that your pet ferret doesn't want to eat food that is good for him. Give sugary foods, including fruits, very, very sparingly. It is a better idea to stick with meat-based cat treats, ferret treats, eggs, and small pieces of meat or freeze-dried muscle or organ meats. Hairball treatments can also be given as good treats because ferrets get hairballs much the way cats do (but they don't hack them up). The oils in hairball treatments can help the ferret to pass any hairballs that do accumulate. There are a number of ferret hairball treats. However, hairball treats and treatments for cats also work well with ferrets. These things should be given only as treats, but can make for a fun time for you and your ferret while adding to their diet (especially if you stick with healthy options such as meats, eggs, cat treats, ferret treats, and hairball treatments!)
Armed with a little bit of knowledge, you can feed your ferret the foods that he really needs to be healthy and happy.