general rule of thumb is they will only survive long term on natural grazing.
you could try putting a pile of rocks under a strawberry container, under some more rocks to make a haven for pods to reproduce away from fish and hermits.
melev has actually trained his mandarins to go into a little jar and eat pellets. I finally got mine to eat some spirulina brine shrimp yesterday so i know it will eat frozen, and have a brine shrimp factory in the works, along with a pod factory, in addition to my fuge and 100lbs LR, so hopefully mine will live a long life on natural food.