I would completely kill. That way you know what you are starting with.

I don't know if Rotenone in Texas is considered a product that you need a license to purchase/use. If so, hydrated lime can be used to kill the fish.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).