Juvenile stage

I can't figure out how long a chinese fire-belly newt is in it's juvenile stage. Aside from the disinterest in water, can I use size as a gauge for age? I know about water quality and cycling an aquarium - if not done correctly they will reject water. I read alot of posts and have found that a healthy newt is one who spends most of it's time in the water and this should be encouraged. However, isn't there a stage where they prefer land?

Yes, for about a year after they first morph is when they prefer water (from what I have been told). This is just an average though...and is true for most species that come from aquatic larva and are aquatic adults, they go through a terrestrial juvienlle stage.

In CFB's it's pretty hard to guage how old they are just from size unless they're abnormally small. I would just keep providing your animal with plenty of options in both land and water, and let him/her choose. If it last for a really long time sometimes some 'encouragment' is needed. Suggestions I've had given to me were to mist the newt daily or to raise the tank water level so that all the land is submerged, but just deep enough so that if they sit on the land their head can break the surface.

I did this, and the three that were clinging to land for about 8 months are now always swiming about looking for food.

Hope that helps, and anybody feel free to add/correct anything I've said.

I agree with Rob 100%. There is no good rule regarding size/maturity. My guess is that if it is over 2.5 inches (6 cm) and over 1 year old, it's likely that it is old enough to adapt to water. Try decreasing the land, remove any hiding places on land, and provide some shallow water for it to get used to.