The victim, a man in his 20s, was assaulted in Roberts in Vineyard Street at around 2.35am this morning, Sunday 8 August.
A 31-year-old man from Colchester was arrested on suspicion of committing grievous bodily harm a short time later.
He remains in custody for questioning.
The staff at Roberts are assisting with our enquiries, but we’d like to speak to any members of the public who may have witnessed the assault this morning.
Please quote the crime reference number 42/161590/21.
You can submit a report online at https:///www.essex.police.uk or use the ‘Live Chat’ button to speak to an online operator between 7am-11pm.
You can also call us on 101 or, if you’d prefer to remain anonymous, you can call the independent charity Crimestoppers on 0800 555 111.
