'Reputation level' is the wrong term for the fishmonger reputation. Actually using such words implefies more than there is behind.
As mentioned before, that myterious reputation splits into two parts:
- total number of quests done. Once you have reached a certain number, you get access to orders with more lines. (Thought it is still random.)
- a reputation thingy per single fish species. You start with 10 fish. After you delivered those, your next order for the same species increases to 15 and after that to 20. (If you never decline an order, you cycle through 10-15-20 for each species individually. If you decline an order, you next requested order for every species of that order declines by 5 with a minimum of 5.) If you do multiple quersts, you might skip parts of the 10-15-20-cycle. If you deliver two orders of the same species to after each other (to the same harbour for example), you cycle two steps. Thats all whatmultiple questing does atm.
- there is a strange reset/revamp of your total number of quests done, when you reach a fishing skill of 106+. When you beginn to get orders for dungeon fishes you get an increased number of low-line-orders until you have done again 'a couple' of them.
(There are more accurate formulars for this system around. But those above are the basics that those formulas base on. For me those basic give me enough informations about how that system works.)