Pond Boss Forums AERATION Systems questions 8 acre pond at 10,000' - lots of aeration ?s

I only stocked 300 Brook Trout from a hatchery in Summer 2017. When they were active this Summer there would be fish hitting all around the lake. My buddy threw out one of those fish finders you pull around with a fishing pole and saw groups of up to 6 "fish" (if that is actually what it was seeing). I really don't know where to begin as far as a guess on numbers. I do know 300 fish in 7 acres is not many to start with.