I plan on doing the same with my 1 goldfish hun, but mines an 11 hour drive. fro all the research ive done this is what i came up with:
(i have 10gal tank so its prob easier for my)
1) dont feed the fish for 2 days before departure, this will reduce the chance of intestinal-related disease in the stress of moving. also he wont pollute his water on the trip. (u may want to do a cleaning and water change the day before too)
2) empty the tank to the point that you can carry it safely (im gonna pour out 5 gallons into a fresh home depo bucket so that i dont have to give him 50% new water when i get there, you may want to do something similar but if its a huge tank, put the fish in 5 gal buckets each)
3) remove decorations from the tank and keep them wet in their own tank water in sealed bags or buckets.
4) get an ac adapter for the airpump so you can keep the water oxygenated in the trip (also if theyre tropical get one for the heater too)
5) put some sort of covering (but not a SEAL) on the top of the tank/containers so that water wont splash out, but air from the air pump can still circulate out.
i think thats all i came up with. its gonna be traumatic for the little guy, so try to keep everything in the tank stable before u leave, and make sure u put back everything (including HIS water, not tap water) soon as you get there. best of luck