it is not impossible, but highly unlikely they will survive long on it, especially when competing for food in a tank with high flow like our tanks will have.
a mandarin jumps all over the rock, then stops... looks at the rock... looks some more... then eats a pod. goes on stops... looks at the rock, etc.
they also can be trained to eat pellet food as well, but what if it doesnt? what if it can't eat frozen? it will be dead after starving to death.