My cages have 4' depth and a cage lid to keep out any predators and that works well. Using a blocking net the fish will more or less be on their own, just like in the main body of your pond, with the regular host of predators trying to steal a meal. I don't think your fish will be appreciably more prone to predation behind the blocking net as long as you have ample depth say up to 4'+.

Many men go fishing all of their lives without knowing that it is not fish they are after. ~ Henry David Thoreau

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