Hi tigwig. Cats very quickly work out who is the softie in the household! With my two cats they know that they can simply open their mouths and cry a bit and I will pander to their every whim. They are demanding and fussy and do exactly as your cat does, tuk in to one type of food happily, then when I confidently buy a whole box, refuse to touch it, infuriating!! My partner on the other hand is not so soft and when I had to go on a work training course for two weeks, just stuck down whatever food was to hand and they had to eat it all or go hungry. They soon learnt to eat it without a fuss. Unfortunately as soon as I came back, it went straight back to normal eating! My cats are now too old for me to retrain and I am too soft to ignore the heartfelt cries, but with your cat there is still hope as he is young!! If you are tougher than I am, then I would stick to your guns and make him eat what you want him to eat. If you are just a big softie, then perhaps someone else will take over feeding him for you? Good luck anyway!!