I don't smoke meat and fish at the same time in the same smoker on the mere chance that the fish will impact the flavor profile of the meat.
In the past, when my family was heavily into fish on certain religious holidays, everything cooked with the fish had a hint of fish in the flavor profile. Meat obviously wasn't being cooked, but there were plenty of roasted vegetables and cheesy pastas. The cross flavors may have resulted from food prep, but it was there.
I have no problem smoking meat, clearing it out, then smoking fish in the same smoker, but some won't even do that. My Texas wife is not a fish eater at all, except on rare occasions. A fish flavor in meat would NOT be well received. Our first Christmas Eve Seven Fish dinner is still one of her favorite stories to tell for laughs.