When I was a teenager I caught two garter snakes in my back yard an kept them for about a year in an old tank with a screen lid. I had a dirt substrate and a coupe of sticks of assorted sizes. I fed them earth worms every other day. It was always so cool when they would shed their skin. They used to flip the screen lid and crawl on top. One day they did it, escaped and we never found them. I'd like to think they got back outside and lived happily ever after.