I played this game for a little while and it has a lot of admin. Current money + value of fish - the cost of the bate every single time. I am getting 5G each time. The next rod (quality rod) cost 100G. I happened to notice the cost of bait increases faster than the value of fish. Quality bait cost 2.25x more than poor quality bait. The large fish are worth about 2x more than medium fish (not accounting for the dices bell curve and the fact trophy fish get more rare the larger they get.)
I feel whoever made this game is allergic to math. There is a 20% chance catching a god fish will not lose you money. Gold tackle will almost always lose you money. The simple fix is to lower the cost of every item.