Water
A regular supply of clean, fresh water is essential for all poultry: sometimes called the forgotten nutrient.

External Parasites: Lice and Mites
The common poultry louse is yellow in colour and flat in shape and lives mostly under the tail. It lays its eggs at the base of the feathers forming a clump of what looks like white sugar. The bird is better off without these, but they are not life threatening. The de-pluming mite is hard to see as it is very small and is usually found in the head and neck region. Northern fowl mite is a bloodsucker and will eventually kill a bird if left. These mites live on the bird and can be found anywhere, but especially under the tail and in the crest of crested breeds. The previous three parasites can be controlled by the use of louse powder (or spray). To apply, hold the bird by its legs, turn it on its back and place on the ground or a table, pressing it down gently to hold it still. Sprinkle the powder under the tail, under the wings, along the body, up the neck including the ear canals, and over the back. Rub the powder well in. Once a month should be enough, but all these parasites breed extremely quickly if left unattended. Even if you don't observe a problem, applying the powder periodically as a preventative measure is advisable.

The red mite lives in the housing (particularly under perches and cracks or crevices) and feeds on the blood of the bird at night and is again a potential killer if left unattended. Available from most pet stores is a good spray for the housing as it is persistent, but every nook and cranny must be sprayed, including under any felt on the roof and especially in perch sockets. With a ten day life cycle, vigilance against this mite is time well spent. Raised and encrusted scales on the legs is an indication of the scaly leg mite. It lives and burrows under the scales and causes intense irritation. Surgical spirit in a wide-mouthed jar is an easy treatment and is not toxic to the birds, unlike other preparations. Dunk legs once a week for three weeks, but it will take a long time, maybe a year, for the legs to look normal as scales grow very slowly but are replaced annually. Again, prevention is better than cure and thoroughly cleaning the legs of poultry with soap and warm water to remove any dirt, then rubbing coconut oil (available in solid form from health shops) into the legs (repeating the process every few months) will help prevent scaly leg mite appearing in the first place.

Internal Parasites
These are usually referred to as 'worms'. there are six different types inhabiting different parts of the hen, most of them in various areas of the intestine. Hens get an immunity to worms eventually but stress (for example, caused by moving to a new environment) can disturb the hen's immune system and the worms then breed wildly and affect the health of the hen. Ducks and goslings can be killed by gizzard worms when they are young, so it is important to monitor the worm burden - any bird off its food or moping is suspect. The easiest preparation which controls all types and stages of parasitic worms is a powder you add to the feed. Tablet wormers given to individual birds are also effective. Some people have had success using garlic, but usually as a preventative rather than cure.