According to the University of California-Davis website (
Toxic Plants), the Ficus lyrata (Fiddle-leaf fig) gets the same toxicity rating as other plants in the Ficus species, which is that the sap can cause dermatitis (itching or rash on the skin).
This has always been the disclaimer when using Ficus plants. The sap could cause irritation to your cham's skin or eyes. Now with a Ficus Benjamina (the one recommended in the Sticky thread), that's not usually a problem, because the leaves are small and hard, and don't store much sap. You should always be careful when pruning these trees that you don't let your cham near them until the wounds from the pruning are fully healed and the sap has stopped oozing from them.
However, the rubber-plant (Ficus Elastica) is usually best avoided, because it has lots of sap in the leaves, and these leaves can easily be punctured by your cham's claws, or if they should bite into the leaf.
I would expect that the Ficus Lyrata, with it's thick broad leaves like the rubber plant, would probably be the same in that there will probably be a lot of sap in the leaves, and the leaves could easily be broken open by the cham.
So to summarise, the F.Lyrata is not toxic, but contains a lot of sap that may cause irritaton to your cham's eyes and skin. It would probably be best to avoid this plant.