The traditional interpretation that a bishop may have one wife is that he may not remarry if widowed.
I also believe that polygamy was largely in the past for the Jews by the time of Christ, but I think you are right that there is not an explicit forbidding of the practice in the Bible. A number of things are not explicitly forbidden: suicide and abortion come to mind. Slavery is condoned (but not established as a good!)
Mrs VS
Thank you. Yes.