Mcdonald,
I have hands on experience with Tilapia and gizzard shad in my East Texas ponds. I have just stocked the gizzard shad, so my experience there is very limited. However I would refer you to the May/June issue of Pond Boss for a great article on gizzard shad. Also read the recent "gizzard shad" thread in which Bill Cody goes negative on gizzard shad.
Some say the gizzard shad will take over your pond and compete with Bluegill. The referenced article refutes that assertion however. In my own case, my worry isn't that they will take over, rather that they will be eliminated by the LMB and HSB before they ever get established. The LMB and HSB have been having an absolute field day, every day since stocking the gizzard shad. You can see the massacre going on in the open water areas of my pond (3.5 acres).
Regarding Tilapia, they are a must have for the southern pond owner, in my opinion. I was told bad things about them (by the so called experts) before stocking, none of which were true. Here's what I have learned first hand: they reproduce like rabbits, clean like a janitor, fight like a banshee, grow like weed, and taste great.
This is based on real, not theoretical, evidence of the value of Tilapia. In one summer growing season, they have transformed my old 1/2 acre "bass" pond from a dead weed, algae infested mess into a thriving system. The bass in that pond are fatter than they have ever been, the bluegill are far more numerous and larger than ever, the algea and weeds are gone. What more could one ask for?
The only unknown for me regarding Tilapia is the cold water die-off. Will that result in a massive fish kill and/or mess to clean up? I doubt it, but time will tell. My water temperature was 61 degrees this weekend. When it hits 50 degrees, I will know the answer.
