Ive had this situation twice where the house has to be sprayed because of
pests in the house. I did the risky move and just covered my tank with plastic and taped it. Luckily, all t he fish survived the ordeal. I dont know how its going to be with fumigation because that would be more intense than just spraying .
I would do the safe thing and move all the fish out. When its ready to move the fish back in, i would also do a major water change . Good luck and keep us posted.