catching it is key, if you stress it too muchw hile catching it can also kill it during transport.
use a thick large bag, black preferably or white out bag. Thick and strong, catch it wtih a bag not net, it reduces and eliminates damage to begin with.
Then put it - the entire bag wtih fish in it in a large bucket or square cooler bin. batt powered air pump will be fine.
2.5 horus isnt that long, i transported large dats for 10 hours before!!