On this page, I see the following listed as a Japanese proverb:
The jellyfish never dances with the shrimp.
Meaning: Enmity is inborn and natural, it can never be eliminated.
However, doing searches in Japanese for this doesn't yield anything online.
My theory is that this is either:
1) A very old proverb which is uncommon.
2) Actually from another language which somehow got back-translated into Japanese.
3) 'Evolved' from what it was originally.
Can anyone speak to the authenticity of this proverb? If it is authentic, can you confirm the meaning as well?