Those 4 are available for Tube right now AFAIK.
Trade on livecoin.net [Most volume] https://www.livecoin.net
Trade on tradeogre [A bit of volume] https://tradeogre.com/exchange/BTC-TUBE
Trade at altex.exchange [Barely any volume] https://altex.exchange/markets&pair=BTC_TUBE
Trade on CREX24 [Barely any volume] https://crex24.com/exchange/TUBE-BTC

Hard choice when you read reviews/opinions about any of those. xD
Its really more of a "forced by volume" choice, than being able to choose around the "quality" of the exchange, which is currently my main issue with Tube. But its really just a start I hope.
...Tradeogre seemed more attractive to me, but livecoin might be more "developed" I guess.

Right now I wouldnt wanna use any of them for other trading, just for exchanging Tube and trading somewhere else.
[ note: Iam completely new to crypto, btw ]

Volumes comparison:


Other useful infos:
https://coinlib.io/coin/IPBC/BitTube
https://cryptjoker.com/ipbc/
https://crypt0.zone/calculator/details/TUBE?hr=3000&pwr=250&ec=0.15&fee=1.0&cur=USD&average=24h&exchange=0