Rowly -I currently have 41 perch in a 12.8 cu ft cage (3.2/cuft) from last years catch, feed training & cage rearing session. I started with around 70 fish (5.4/cuft). Expect similar results as far as survival. Some perch died, some did not learn to eat pellets and a few of the smallest perch may have been cannibalized. Current 41 fish were sorted and culled in October of last year from 50 living fish. 200-300 is a good number to begin with in a 4x4x4 cage without supplimental aeration. Try to minimize the length of time that the 1st fish are in the cage compared to the last fish going into the cage before you begin feed training. I think you will have better success if you begin training when final batch of fish are introduced into the cage.
I have successfully feed trained perch at as low of densities as 1 per cuft (12 perch /12 cuft). I will email you some feed training suggestions for perch. If most or if all of your current pond perch are truly wild and not from domestic stock then your survival rate and feed training success may be somewhat lower than mine.
For your growing zone and initial estimated starting sizes, expect growth increases of 1"to 2" on the fish by fall if you start in early to mid May. Females will grow faster than the male fish. Final sizes of most fish will fall in the mid to upper size ranges (1.3" to 1.7" increases). Worst case senario is you end up with only a few pellet eating perch and gain a lot of experience from this project.
