Not the sort with fish in it!
The idea of this is to set up two circles – an inner circle and an outer circle. The inner circle have a discussion while the outer circle listen to the discussion. The outer circle give feedback about the discussion after having observed it.
The focus for the outer circle is observation and listening skills. You can ask them to focus on specific things such as summarize what they have heard or perhaps ask them to have a focus linked to the Oracy Framework.