Mutant River

Mutant River is the fifth location in Zombie Fish Tank, it consists of the river where the fish previously was, it has a dark forest background, the water seems dirty.

Boss
The boss of Mutant River is the Hidden Snake, it its a snake that only its head and tail can be seen, it has a light in the head, if it is defeated, the sixth location (Freak Wreck) will be unlocked.