Wulin Gaiden is a mobile game and Catfish and Yellow Flower Fish are two of the special fish. According to my understanding, Catfish and Yellow Flower Fish can be obtained from the game's fish pond.

There are several ways to get Catfish and Yellow Flower Fish in the game:

1. Fish Pond Catch: Use the bait in the fish pond, wait for Catfish and Yellow Flower Fish to appear, and click Catch as soon as possible to get them.

2. Special Events: Some special events will appear from time to time in the game, and you may get catfish and yellow croaker by completing these events.

3. Store purchases: Catfish and Yellowtail may be purchased in the game's store for in-game currency or real money.

It should be noted that catfish and croakers may be available in different versions and updates of the game, so it is recommended to check the in-game instructions or talk to the game developers.