See if he will climb into a jar or net? I always kept them in the bag and once acclimated in the bucket, poured out most of the water from the bag, put the bag in the tank and let them come out at their leisure.
He'll come out of the bucket when he's ready, then grab out the bucket so it doesn't become a den if you don't what it in there. It won't take long for the tank to become more interesting. Give him lower lighting for this first night to help him settle in!