If (you live in the U.S. and) you have ever bought freshwater fish at:
- Walmart
- Petsmart
- PetCo
- Pet CLub
- any other regional chain
- 95% of local pet stores
you have bought fish that have been shipped by mail, at least twice. (Usually once by air, once by ground.)
The way the fish industry works is that mass breeders (mostly in Thailand and other parts of Asia, although there are a few in Florida and other warm parts of the U.S.) breed the fish, then ship them by mail to a wholesaler. Again, most of this shipping is done via air mail, from OVERSEAS.
The wholesalers then compile their weekly stock list and email or fax it to all their local customers, both "big box" stores and LFS's. The vast majority of the stores (and all the "big boxes") then email or fax the orderform back with what they want. The fish are then bagged up and shipped to the stores--sometimes by "proper" mail (USPS, UPS, Fed-EX), sometimes by a driver that works just for the company, who will run all the boxes to all the stores in the area.
Most marine fish get shipped THREE times, since teh vast majority of species are still wild-caught. They are collected by divers, then shipped to a central broker who has an import/export permit and handles the catches of several different companies/dive groups. The broker then ships the fish to the wholesaler, then the wholesaler ships to the store as mentioned above.