There is a Relative Weight chart in the archives. It doesn't specifically break out F1's, just LMB in general. If yours are heavier than the ones on the chart then you are doing well.

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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).