Baby bearded dragons love having loads of space to move around so it's absolutely fine to house them in a large vivarium that they'll grow into as they get bigger. Don't bother housing them in a 3ft vivarium and then upgrading them to a 4ft one; they won't be overwhelmed by the extra space.13 Nov 2015
Is a 40 gallon tank too big for a baby bearded dragon?
Babies can live in a 40 gallon tank (38” X 18” X 18”), but that is as large as I would recommend for a baby bearded dragon. Some babies could have difficulties catching and eating their food if their enclosure is too large, larger than the 40 gallon tanks.5 Nov 2020