A passer-by spotted the baby in the water at Rough Wood Country Park, off Hunts Lane, in Willenhall, at around 1pm on Thursday, May 20.
Police have now launched an investigation into the circumstances – and are appealing for anyone with any information to come forward.
Officers are also carrying out house-to-house enquiries nearby and checking local CCTV.
Detective Chief Inspector Jim Munro, from West Midlands Police, said the force's main priority was to find the mother of the baby – and get her the medical attention she needs.
Speaking to the Express & Star, he said: "So we were called to the area around 1pm yesterday afternoon by a passer-by who had found what he believed to be a baby floating in the canal. Enquiries then immediately got underway, a scene was put on and the tragic discovery of a little baby boy who was dead was found.
WATCH: Detective Chief Inspector Jim Munro's appeal after baby boy found in canal
"We have since started local CCTV searches, house-to-house enquiries within the area – however, our direct appeal really is to the mom to come forward.
"The little boy could have been in the water for up to four days so ultimately our priority is to get her the medical support she needs following giving birth.
"Also there may well be family and friends or people who know someone who may have been pregnant recently who no longer is.We would ask them to come forward, whether that is anonymously, to provide us with information to help progress the enquiry.
"But also the area itself, in and around the canal, we know there is a lot people who frequent the area – walking, boating, if they may well now in hindsight seen something in the last couple of days that may now have aroused some suspicion, to come forward and provide us with that information to help us try to identify when that little boy tragically went into the canal.
He added: "The CCTV searches and house-to-house enquiries are very much in their early days, what I would ask is if people have information around suspicious behaviour that they come forward so that it might allow us to start pinpointing timescales to make those enquiries more directed; because at the moment we are working within a large window and we need to keep an open mind until we have such information to allow us to start going down a particular path."
Speaking about when the little boy may have come to be in the water, DCI Munro said: "Potentially he could have been in the water there for up to four days. However, we are working with experts to try narrow that timescale down to try and understand how the little boy has died and also the mechanisms surrounding that.
"We are working with British Waterways to understand the tidal flow of the canal, the speed and the amount of water we have obviously had over the last few days. However, our belief is that the little boy has gone into the water in and around that vicinity and around the area.
"So it is probably not far from where the little boy went into the canal but we continue to work with experts to try understand and pinpoint that location as best we can."
Appealing directly to the mother of the baby, DCI Munro added: "We need to get you that medical support and provide you with the support you need following giving birth. That is our priority.
"We will ensure you will get that support if you come forward.
"We are also working with partners in health, social care and education to see if they can help us identify his mother.
“I realise how distressing this tragedy is for the local community, but please don’t speculate on the circumstances of this upsetting incident, it hinders our investigation and is painful for those involved."
Chief Superintendent Andy Parsons, from Walsall Police, said: “I’m shocked and saddened about this deeply tragic discovery.
“My thoughts are with him and the wider community who I know are upset and concerned about the nature of what happened.
“We’ve got local officers in the area offering reassurance, please do speak to them if you have any concerns."
Anyone with information can call West Midlands Police on 101, quoting incident number 1963 of May 20.
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org