Hi.

 The image itself looks good, though both the lobster and the crabs are crustaceans* i think.
On the other hand, the guidelines of the contests require a Mockup for a game. You should include a HUD or some indicator that this is an interactive fight.

Other than that good result with that pallete. :)

*Crustaceans are arthropods but I consider that a "valid Arthropod" would be a scorpion a spider or a millipede. but that's just me.