We've discussed the matter of flatheads (FH) in the J in previous threads and I recall there was some speculation that habitat is limited for them.
While I don't want to see FH spreading, it's inevitable that they will go right up the J to the dam below Petersburg. However I wonder how many FH will "stick" in the J? This is a shallow river and while there are log jams at the bridge pilings, there is just not a lot of habitat comparable to what one sees down in the impounded sections of the Susky where FH are currently so numerous.
It may turn out that FH come to be associated with a couple of the deeper pools in the J but that, overall, there doesn't turn out to be many of them in most of the river(?)
Keep us informed of news of FH in the J - interesting topic.