I'm in San Francisco, and I ran into the same issue.

Also, here across the bay temps run a bit lower, and so I figure that I'd have to run a heater to raise tilapia as well, and I don't really want to do that. Also, one of my favorite crops is broccoli and in order to prevent bolting broccoli needs water temperatures that are lower than then the healthy low end for tilapia...

I should say here that I've *just* cycled my first IBC system and I'm about to stock my first fish.

I'm to try koi. Koi are basically just fancy colored common carp. As carp they have some very good properties.

1) They are tough a heck
2) They like colder water
3) They eat just about anything (though for best weight gain a well balanced diet is critical)
4) The put on weight pretty fast (not as fast as tilapia, but faster than a lot of other fish)
5) They will breed quite easily in captivity, so you can raise your own fry with out having to mess around with hormone injections
6) They are widely sold and raised all over the Bay Area.
7) They are really quite beautiful!
8) They are excellently tasty with a flaky mild flesh. In Europe and Asia carp is the #1 farm raised fish consumed by volume.

Downsides
1) The don't put on weight as fast a tilapia. ( think that they are more like cat fish, and they are better than trout or pike)
2) They are harder to fillet than tilapia because they have an extra set of bones... but after your first go, you get the hang of it and it's not that hard.

But as I said above, most of this info is just book learnin' for me. (except the taste & fillet info). I've just cycled my first IBC system, and I am going to order my first school of fingerlings this evening. So please take this all as somewhat ignorant suggestion rather than any sort of informed advice.

B