Need to Make Middle Layer That is Unaffected by Other Effects in Upper Layers

[Dirthmitore]

I have a scene with a number of layers, lighting, random blurring, and foreground objects. Then I put a fishy cartoon character in there.

But then I want the fishy to be able to go behind the coral and anemone. But putting him down below all those other layers means that he is going to be affected the same way as everything else.

I assume that pre-composing the foreground elements will be the only way to get that stuff in front of the fish, but won't the effects in the transparent part of the pre-comp carry over into the full comp, and affect the fish layer?

[Dave Merchant]

The tie-in between layer order and effects inheritance is a limitation of After Effects' workflow, and why many people prefer node-based applications. There isn't a simple way to disable the inheritance, but you can sometimes sidestep it - in your case the simplest solution would be to make the layers and composition 3D, then very slightly nudge them apart in the Z direction until the fish is stacked between the other two. That way the layer order in the composition can be different to the visual stacking order in the video. Note that 3D always sees the scene through a perspective camera so there will be a scaling effect when things move in Z, but with tiny offsets it won't be noticeable.