Optimizing game for Android device. Problem in using Particle system and environment fog. Also Build size is high.

I am working on FPS game for mobile platform. I have used particle system in it but when i test it on my mobile platform it shows black also the size is 600mb for android build for ATC format but when i build it for iOS its coming 189mb. Can anyone please tell me how to optimize this and how to use particle system and environment fog for mobile platform.

@Fighter5347 can you help me with this?