Depending on time of year, and where you are, and where the fish are going to go, you will also probably need to invest in lots of heat packs. Although you expect fish to arrive in 24 hours, if that's the shippers agreement, with weather and other delays, it sometimes takes longer, so the 4 day heat packs are good insurance.
I sent a package from Milwaukee to Utah, that was supposed to take 24 to 36 hours, and it ended up taking 4 days +, due to weather, and time on the truck after landing.
If you use the USPS, and a package arrives late, you can recover shipping costs, but with some of the other shipping companies, this is not available.