One of my earliest memories was riding on the back of my Fathers bicycle to his allotment to tend his vegetables and gather the seeding heads of the weeds that grew there and as much chickweed as he could carry, his passion was Canaries and Native British Finches and their diet comprised of as much natural food as he could find. He used plants to brew tonics and cures, I never discovered what he knew, he died when I was 8 years old and I at the time beyond listening to canaries and mules singing had no real interest in keeping birds myself, although a few things he told me I still recall, he said "there is a difference between surviving and thriving" he understood the importance of nutrition in preparing his birds to breed, the management needed at different seasons of the year in order to have his birds fit and ready for the task ahead for when he paired them up.  I recall looking at canaries brooding their clutches each cage covered with seeding heads of weeds and chickweed, him making rearing food from sausage rusk and hard boiled egg daily, after his death my Mother disposed of his birds and equipment but some cages built into a small shed remained and after life had returned to some semblance of normality my interest turned to using them for bird-keeping.                                                     
Diet can turn a bird into a fit and healthy specimen that lives up to our hopes in the breeding cage and on the show bench.The Bengalese Finch is a seedeater that shows a marked preference for certain seeds, White Millet, Plain Canary and Panicum Millet along with Paddy Rice are the preferred seeds for the majority of birds. A diet comprising of a good Budgie mix with a low percentage of Plain Canary supplemented with additional White Millet in the mix and Paddy Rice, (this is best supplied in a separate dish) will provide a good maintenance diet.Heading towards and during the breeding season your birds will need a softfood to condition them for breeding and assist in rearing their young.Another useful aid in this process used by many fanciers is soaked or sprouted seed.
There are many types of softfood available from plain bread and milk to complicated formulas from bird food companys. It is perhaps best to choose a ready formulated softfood that contains the vitamins and minerals that are needed by growing chicks.
Always provide a supply of mineralised and oystershell grit to your birds.
Water is the most important component in yours bird's environment both for drinking and bathing, and a clean fresh supply for both purposes should be provided daily, more often were possible.
Most birds will eagerly consume Greenfood that is fresh and clean and gathered were you are 100% certain there is no contamination, Chickweed appearing to find the most favour.
Supplements in the form of, Vitamins, Minerals, Liquid Calcium,Probiotics, etc, are appearing more and more and the best of them can assist in a properly formulated diet plan, but care should be taken and advice sought on their proper use.
As you gain more experience with your birds and read and talk to other fanciers you will find the system that suits you and your birds, that brings you the breeding and show successes you are looking for. When you reach this happy stage remember “if it ain’t broke don’t fix it”.
Cleanliness around the birdroom is of paramount importance, due to our bird's confinement they are constantly in contact with their droppings stale eggfood etc, and illness in these conditions is lurking around the corner. We don’t need an operating theatre environment but the cleaner we can keep our cages the less chance we have of trouble flaring.
It would be impossible to give even a brief outline of health problems in this small article, but I would advise a good book on keeping birds, if possible one specific to finches be obtained, as the advice in these books concerning illness and injury will apply equally to the Bengalese.                                                                      

Opposite is dry softfood before mixing, and softfood packed with peas, I use frozen peas in my softfood, I blend them and add to the softfood most times this means I never need to add any liquid other than that which is in the peas, my birds consume the peas with relish and stuff the youngsters full of peas and softfood, peas are in my opinion a great addition to your birds diet when feeding youngsters.