Blue spots may like cooler temps but they can take temps up into the 80's with no trouble, I have dove the Sea of Cortez and collected them with commercial collectors in the late 80's early 90's several different times. The reason they don't do so well has to do with how they are collected and handled before they get to the local stores. I have posted on this in the past but here is the methods used by the collectors for the aquarium trade back then, I can't say if they still use the same methods but I don't see why they would change, this is almost 100% effective if the fish is in the hole they choose.
They take 2 inch PVC couplers and tie a plastic bag or net to one end. Then they dive until they find a colony. At this point the good collectors take old, spoiled milk in a squirt bottle and squirt some down the hole and put the open end of the coupler over the entrance to the burrow, then move to the next hole and so on until they collect as many as they have traps for. This is what the good collectors do, more often then not the guys down there use bleach instead of milk and the jawfish not only come out so much faster then with the milk but they stress out and they lose a portion of the catch before they get off the boat. These fish are doomed to die no matter what temps you keep them at. I dug 7 out of holes on one trip and kept them for several years with the only ones that died jumped out of the tank, most of them lived until I moved and took the rest to a local fish store because I didn't set the tank back up at that point. I lived in San Diego and the tank was up in the mid 80's all summer and fall, but cooler in the winter/spring. My experience and opinion is they are going to live or die because of collection and handling that happens long before they even get to the local store rather then tank conditions in your tank.
The sad thing about this is no one is going to tell you this mostly because they don't know, and it is illegal to collect this way so the collectors are not going to admit it. I have actually seen this with my own eyes so I know it is true, but most stores don't get the chance to send someone there to dive with collectors. I have collected for a living in the past and have dove with collectors all over the world to watch different methods. It amazes me that some fish are ever seen alive in the pet trade after watching what they go through before they are even sent out of the native country.
