IF you can figure out a way to keep them out of the pond in the future, I'd nuke the pond to kill the GSF and start over. They will eat a tremendous amount of fry that hatch in the pond. Been there, done that and nuked the pond, starting over because of 0 recruitment of the stocked 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).