It looks like you're trying to combine some different phrases:
* Swimming in the deep blue sea: This describes an activity.
* After you me eat up: This phrase is grammatically incorrect and doesn't make sense. It seems like you might be trying to say "after you eat" or "after I eat".
* Oh yes he will: This is a phrase that implies someone will do something, but it's unclear who "he" refers to.
* Cause a bad fish: This could mean that something will make a fish sick or unhealthy.
To create a meaningful sentence, you'll need to clarify what you're trying to say.
For example, you could say:
* "Swimming in the deep blue sea after you eat can cause a bad fish." (This implies that eating something before swimming could make you sick and potentially harm a fish if you're swimming in a place where fish are present.)
Let me know if you want to try to clarify your thought and I can help you create a proper sentence!