What I would suggest:
Whole Menhaden Meal 38%
Soy Meal 29%
Corn Bran 24%
Wheat Flour 9%
Lysine may be needed to complete the Wheat Flour amino acid profile
Protein Digestibility 88%
30 Points of Energy
Protein 40%
Fat 5%
Starch 19%
Fiber 19%
Ash 7%
Moisture 10%
At 38% whole fish meal they should eat this food really well.
A little fiber passed into your pond won't hurt a thing. If you ask me it beats the hell out of chicken heads and feet and pork blood.
In the aquarium fish food world this is very inexpensive. In the pond fish food world maybe not. However I have learned with higher protein digestibility you can feed less and get equal or more out of it than lower quality feed.