Warcraft: How to make 64,000g levelling fishing!

$64,000 question: How do you get rich fishing in WoW? I’ll probably insert the screengrabs tomorrow, but suffice to say I am making up to 2,500g an hour simply levelling fishing from 450 to 525 on alts. Today, on my druid, I made over 9,000g – just fishing – while...