The amount of time you’ll have to earn the required Fish Points to hit the next level changes depending on the level you’re trying to reach. In Fish Buffet, you move down levels as well as move up levels. If you don’t reach the required Fish Points in time, you’ll drop down one level.
If you prefer to receive a fixed weekly cashback, you can opt for Platinum Rank. You can choose to switch to a lower Platinum Rank of lower statuses to receive fixed weekly cashback for that level.
You may find out more here.