i throw in carrot peeling, celery/brocolli stubs, leftover lettuce and varous fish pellets..
i find they eat the pellets a lot more readily if you moisten them first..
I wouldnt recommend to ship in winter, however Theo and I did ship a 2' 10 yr old rtg to manitoba, total time in bag was about 8 hr's and it arrived and is doing fine :)