Calling the airlines won't help. I was told by a Customer Service supervisor at AA that there would be no problem checking my fish as baggage. I'd just have to pay $50 for each box over my checked baggage limit. When I arrived with over a dozen boxes of fish, the desk attendant said I couldn't check in the fish. I spoke to a supervisor that told me that the CS supervisor had made a mistake and that the airlines don't allow fish and reptiles on their passenger flights. I had to then cancel my flight, lug the fish (I was on foot since I was dropped off) to the cargo terminal (only to find outgoing packages closed til morning), then re-lug all of the boxes (plus my luggage) to the terminal post office. The PO was happy to ship my boxes for the mere sum of $950+. Then, they rerouted half my boxes to Chicago (instead of MS) and ran over one box (crushing my largest female FRT). Over $4,500 of the rerouted fish were DOA.
Save yourself the hassle. Don't try bringing your fish. A long flight will only stress you out over their condition. Buy your fish after arriving at your final destination.