This is exactly why recommended adding the shad; read somewhere that for some as of this time unexplained reason that shad cannot grow big enough in any body of water NOT to be able to be easily eaten by higher tier predators. Do not know what this seemingly built in genetic "restriction" is evolved for but apparently this "rule" is valid. If the predators present can only swallow a 3" shad, the shad do NOT grow larger than 3" long, just barely old enough to spawn once. If the predators can only swallow a 12" shad, shad will only grow to 12"...and would LOVE to catch something able to choke down a whole 12" shad ! Shad convert plankton directly into mobile swimming fish food on the fin and can significantly "boost" a pond`s productivity.