Sketch idea for 'Alien Tales', (working title)

I am working on a script for a 5 minutes animation.

On a remote planet lies the island of Kelpifera. Despite being surrounded by sulphuric acid sea and built on a bed of stinky seaweed, its main attraction are the many fish restaurants
popular in the whole galaxy. The fish is produced industrially in a gigantic under-water factory...
For this sketch I decided to play around with Photoshop, as I would like to become more comfortable working with it.