I'm no expert but you're going to need some structure in order to get the fish successfully reproduce. Without places for the fry and YOY to hide they are going to get wiped out by predators. Theo's asking about your management goals in order to give you more specific advice.

JHAP
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"My mind is a raging torrent, flooded with rivulets of thought cascading into a waterfall of creative alternatives."
...Hedley Lamarr (that's Hedley not Hedy)