I did some research on ferns a little while back, and the entire fern family seems to be safe and nontoxic. The ASPCA even has a poison control page on their website with safe and unsafe plants for pets, and all of the ferns I've seen listed are on the safe list.
Thank you Erika. I searched this forum before and couldn't find about australian fern and some threads said that not all ferns are safe for torts. The only fern most people know safe is only boston fern.
So I open this ASPCA site and those plants listed safe are for cat, dog and horse. Are they okay for torts too?
The toxic plants are on that list because they are known to contain certain components that can cause illness or irritation when ingested by anyone--human, dog, cat, whatever. The fern family supposedly does not contain any of those components, so are therefore considered nontoxic.
I have a bunch of fishtail and staghorn ferns on my property that my torts have access to. They've never even shown any interest in them. They'd much rather eat grass and greens. I, personally, believe ferns are a very safe option for tortoise enclosures, and would not hesitate to include them.
I personally would like to put the australian fern in the enclosure as they have the ability to filter air, but I saw my tort try to take a nib on that plant before. So I need to be more sure on the safety.