Key details:
The incident reportedly occurred around 9:20pm on Saturday 10 August on the seafront promenade by Undercliff Road West.
Police were called to a Carr Road property at 10:30am on Sunday 11 August, where they found the victim dead.
A post-mortem indicated the cause of death was a traumatic head injury.
The suspect was arrested on Monday 12 August and is being questioned at Martlesham Police Investigation Centre.
What they're saying: Detective Inspector Mark Hughes said: "Investigations into the man's death continue. Detectives are making enquiries, looking into the circumstances of the altercation and identifying those in the area at the time that may be able to assist with the investigation."
He added: "It is important to note that we believe this to be an isolated incident with no wider threat to members of the public."
Police are seeking information from:
Witnesses to the assault on the seafront
Those with CCTV or video doorbells between Ranelagh Road and Undercliff Road West
Drivers in the area between 8:30pm and 9:20pm with dash cameras
How to help: Anyone with information should contact Suffolk Police, quoting crime reference 37/45286/24:
Online: www.suffolk.police.uk/tell-us
Phone: Call 101
Anonymously: Crimestoppers on 0800 555 111 or www.crimestoppers-uk.org
In emergencies, always call 999.
