John,

I'm not aware of a sterile Tilapia and even if there was one it would be almost worthless. The beauty of Tilapia is that they reproduce like rabbits and they die off each year in temps below about 55 degrees. Because they die off, you do not have to worry about them escaping and populating rivers and lakes, in most regions of this country....exceptions being south Florida, south Texas and water that is heated such as power plant lakes.

As to types of Tilapia, there are several. In Texas we can legally stock the Mozambique Tilapia. Other locations have Nile or Blue Tilapia. Check your local state regulations for what is allowed.