However, the Championship club are reportedly willing to allow the Nigerian front man to leave Vicarage Road for £6 million, suggesting a potential last-minute swoop remains a possibility.
Ighalo, 25, moved to Watford from Udinese in the summer on an initial loan deal, but his spell was made permanent in October after the Serie A outfit released him from his contract.
The former Lyn forward has netted 11 goals in 21 league games so far this season, with eight coming since Christmas, helping Slavisa Jokanovic’s side remain in the promotion hunt in the process.
Hull and West Brom are two of the lowest-scoring sides in the Premier League this season, both recording just 20 goals in 23 games, with Aston Villa the only team to find the back of the net on fewer occasions.
Both could certainly do with adding help up top during the closing stages of the transfer window, but it remains to be seen whether there is enough time to make a deal happen,.