It depends on the size difference.
If they are similar in size and weight, then yes, I think it would be okay. (That is if they all tolerate one another and don't fight. Also remember you need to be ready for eggs and to properly care for gravid females.) If he is much smaller than them then I would not recommend it.
Also, if you have newly acquired him, make sure to quarantine him for a month or two before exposing him to any animals in your collection.