The 24-year-old man and 21-year-old woman have been helping police with their inquiries.
The body of the man in his 20s was recovered from the river by officers from the force’s underwater search team on Wednesday.
The death is being treated as unexplained, as officers piece together events leading up the man’s death.
An Avon & Somerset police spokesman said: “We are keen to hear from anyone who was in Hanham area near to the River Avon on Wednesday afternoon – possibly people walking their dogs or members of the public walking alongside the river – who may have information to help us.
“Anyone who is able to help, is asked to contact Bristol investigations on 101, quoting reference 0476 of September 30.”