the leaf behind is clearly showing chlorosis, if it is an old leaf this is natural. if a young leaf it needs a feed with magnesium in it to make more chlorophyll. epsom salts will do the job well.

the leaf behind looks like a normal leaf drop to me - I'm interested in what this plant is growing in and where it is.

Thanks for the sugestions. I have 8 of them in 2 -3 ltr pots that I bought from one of the top nurseries to sell on. I have recently potted them on from 1 ltr pots, so there should still be plenty of nutrients in the compost. I have a south facing site so have tried to move them around to use the shade from larger shrubs. I think the problem was the heatwave we had last week - I'm sure Fatsias prefer shade. Then we had frosts at night. I didn't think it was chlorosis, as they are not really acid lovers?

Chlorosis just means yellowing of leaves - sometimes caused by shortage of iron in acid loving plants, but chlorosis is also what happens when a leaf starts to die in the autumn. Or with normal leaf loss. I certainly don't think the silvering effect on the leaf is a serious issue.