Hi Denise, welcome to aquaponics and to this forum.  Good question re tilapia.  State of CA does not allow them for you or anyone else north of the Tehachapi Mountains, so not in Sac.  I'm not a big fan of tilapia here also because they require tons of supplemental heat (read "$$$ and pollution") to get through even our mild winters.  Better to choose a temperate-climate fish for our temperate climate I think, rather than a tropical fish.  I just wish other fish grew as fast as tilapia...