I doubt you would be charged simply for owning the fund within the IRA.
You might be charged more than you would like to buy more of it and that may be the biggest issue after the transfer.
There might be a minimum balance requirement--Fidelity might frown at you owning say only $1000 worth of the fund. I'm not sure. Fidelity usually has minimum balance requirements, but they may apply only to Fidelity funds?
Your current company (Vanguard or whoever) will probably charge something for the transfer out.
But I don't think Fidelity charges IRA maintenance fees for the account itself.
I have had an IRA with Fidelity for a long time and have owned several non-Fidelity funds within it. Never been charged anything.
Call them to confirm.