Rainman,
Blue is the most invasive tilapia in the south, its ability to adapt to the cold is a good guess as to why, just as you suspect.
The hybridization will soon make it difficult to tell which is which.
The hybridization already makes it almost impossible to find pure strains anymore.
Except for the roughly 10 degree cold tolerance differance, Blues and Mozambiques are very similar in respect to diet and spawning. Blues may eat a bit more algae and Mozambique mature 3-4 weeks younger.
Nile tilapia generally don't become sexually mature till around a tear of age so they are not very well suited in a pond for forage, but could be a candidate for mainly plant control in some ponds.
