20 fish is a lot of fish in hot weather for any live well. especially when you have some hogs in there along. Did you have the recirculator turned on? I would suggest investing in some of those Keep alive tablets, or what ever them things are called. We also drop a 2 gallon bucket on a 10' rope over the side to pull up cooler water from the lake to dump in our live wells too. Seems to help on hot days.
Since it is a new boat, I kind of wonder if maybe there may of been some cleaning product or adhesive residues left behind in the live well or it's aerator/recirculator lines.
Sorry to hear about your mis-fortune. We lost a tournament from the same thing happening to use out of a Bass Tracker's live well. Several people told me it was because they have no insulation in them, and they heat up too fast. I don't know what happend for sure, but it sucks when that happens!
Better luck to you in the future.
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