45g new fish keeper fire eel common pleco

Hello, I recently cycled a brand new tank, a 45g. I have 4 platies and 1 common pleco, with a fire eel on order. I know how large common plecos get, the questions I have are about 2 fish A) How long can I grow my pleco out in this tank and B) How long can I keep a fire eel in this tank before...