Thank you for choosing Ask an Expert for help with your fatsia. This tree just looks hungry. If it is a well-established plant, it may have used up the nutrients in its root zone.

I would imagine that it’s the oldest leaves that are yellowing. When not enough nutrients are available in the soil, a tree or shrub will use the nutrients in the oldest leaves to help make new leaves. Then it discards those old leaves.

A couple of applications of a tree and shrub food this season should help. One now and one in a month. Nothing after August, though. After that, once a season is fine.

Have a good gardening year,