Welcome

I'm also in Sacramento and also have two wild caught adult garters just like yours. They're Thamnophis elegans elegans. In my experience, and everything I've read, they're pretty easy to switch to rodents. Just scent it heavily with fish the first couple of times or put it in the bowl with one or two live fish. When I switched my male I scented the pinky mouse with a frozen minnow the first couple of times and now he prefers mice to anything else. The female that showed up in my driveway last summer was even easier. I 'brained' a frozen thawed pinky(stuck the knife through it's skull until some fluid ran out) and she took to the pinkies right away. They both like the occasional live fish, but really prefer frozen thawed mice over frozen thawed fish fillets(tilapia/trout/salmon) and neither likes worms. What you're doing obviously works for your snake, but I'd try to move away from the goldfish if you can.

I'd love to see/hear more about your snake, too I have pics of my guys here: http://www.thamnophis.com/forum/gene...amis-kids.html