Cody Fisher, 23, a non-league footballer and school sports coach, was attacked at The Crane nightclub just before midnight on Boxing Day.
The murder suspect, 22, was held in London at about 03:00 GMT, police said.
An application has been made for the club's licence to be reviewed, with officers describing "scenes of chaos".
Four other people have been arrested in the capital on suspicion of assisting an offender.
Two were held on Wednesday and two on Thursday.
In its application, the force said it was calling for the review due to the nature of the crime and the "serious management failings of the premises concerned".
It also described a scene of chaos on the night with "hundreds of small drugs bags and nitrous oxide cannisters" evident on the dance floor.
"Oblivious" staff members had begun cleaning up the crime scene after the stabbing, according to one sergeant's account.
"While officers are doing CPR, you can see people are just wandering around in the scene freely.
"As soon as we had more officers on the scene they were removed and the whole dancefloor was cordoned off and the area was made sterile," the sergeant said.
An event planned for New Year's Eve has already been cancelled by the venue.
In a statement, the management of The Crane previously said its staff were "deeply shocked and saddened" by the incident.
In response to the review of its licence, a spokesperson said: "An expedited review of a premises licence is normal whenever any serious crime takes place at a licensed premises, and we are cooperating fully.
"Whilst it would be wrong for us at this stage to react to individual, anecdotal accounts of the circumstances that applied on Boxing Day, we do employ extensive and professional security procedures for all public events, and our contracted security staff are professionals who are licensed by the SIA.
"But we will of course be conducting a full and detailed review in light of this week's tragedy, as well as assisting fully with the ongoing police inquiry."
Det Ch Insp Ian Ingram, from West Midlands Police, said, with seven people in custody, the force was continuing to "build a picture of events" that had led to the murder.
"We are determined to get answers and justice for Cody's friends and family, and won't stop until that happens," he said.
"We are keeping them updated with developments as they happen and continue to support them through this awful time."
People were continuing to come forward with information, he added, but he issued a fresh appeal for anyone else at the club on the night to get in touch.
"If you have footage that we have not yet seen, or you know what may have happened in the lead up to Boxing Day's awful events, I'd urge you to do the right thing and speak to us right now."
Tributes to the player have been posted on social media, including one from Jess Chatwin who said: "My baby's smile how can you take him away. It was meant to be us forever. I'm so sorry my baby you didn't deserve this."
Walsall Football Club, where Mr Fisher had previously played, held a minute's silence before youth team training on Wednesday.
Woodrow First School, in Redditch, Worcestershire, where Mr Fisher coached children, said everyone had been left devastated over the "tragic and needless" death of the "bright, friendly and talented young man".
Tributes will be held at a match against Stratford on 2 January, Bromsgrove Sporting chairman Mike Burke said.
He added the event would be an opportunity to "show our love and respect to him on that day".