Hob should not be with any gills for at least 6 weeks after op till his tubes empty and he is fireing blanks.
A had a hob done a couple of years ago was ok first season after his op and took the gills out of season no bother next season put him with the gills and they were all expecting his tubes had reattached according to the vet this can happen she has just done my new hob cheap 3weeks ago so he has at least another 3 weeks to go before he can get don to buisness