I have very big gold bonus 

The gold bonus doubles the amount of gold you earn in a fight, that is, if you earn 200 the gold bonus doubles it to 400 and that's all it does.I also have a very large gold bonus because there are not many enemies that give so much gold to spend 100k of gold bonus

Is the gold and EXP boost from the fish permanent, or temporary? Nothing in the game indicates how it works.