Neither Grass Carp or Catfish make FA a significant portion of their diet unless they are really, really hungry. The way to combat the algae is either chemically, or get other plants in there to utilize the nutrients before the FA can.

Yes, there are freshwater shrimp, and they are good for the pond - forage diversification.

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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).