Six people were injured in the disturbance outside the Railway Club in Wakefield Road at about 4.30am on Monday.
Seven men aged between 20 and 32 have been arrested in connection with the offending and have since been bailed pending further enquiries.
One male remains in hospital where he continues to receive treatment for his injuries, which are not thought to be life threatening.
Detective Inspector Matt Walker, of Bradford District CID, said: “We would like to speak to this male as we believe he may have witnessed the incident and may have information which could be of use to our investigation.
“We would also be keen to hear from anyone else who can assist with our enquiries into this incident.”
Information can be reported to Bradford District CID on 101, quoting crime reference 13180154054, or anonymously to the independent charity Crimestoppers on 0800 555111.