My opinion is that it is 50/50. Fish survive more than two days coming from overseas..very few shops actually send them overnight! Be real!!
Most reputable betta breeders ship expecting a possible two day delay.
Bigger heat packs, more water. Betta of course are more adaptable.
I see the poor salt fish and anenome at one shop, I have seen the labels. They are ONE WEEK in transit .
How long you can expect? is for how long it was packaged for.
The better insulated and more water..the better survival.
Package markings count too. If it is not marked fragile and perishable or live; it may be put in temp extremes or rougher handling. If it is marked LIVE it always gets special handling...even the good ol USPS does so (I am a postal delivery driver
). There are new bags that let oxy/nitro exchange like a membrane, but you ship less fish because the way they are set up. boxes are not airtight..unless it has six layers of duct tape
, but bags usually are....
We had a betta get lost in the mail 2 days(5 day in a box..packing day shipping morning, 2 lost days and dedlivery day). the box was still warm and the 3 bettas frisky.
If the shipper did everything right, but just had less water, then it is a combination of shipper and shipping agent. It should be insured on his end if it is express or priority tho. At least for return of postage. Check you box markings and go from there... :?