>>40061200Feebas only appears on something like 4 randomly determined tiles in a very specific lake, that you otherwise wouldn't think is special, and they shuffle around.
In some games its every 24 hours, not sure what else causes it.
Feebas is also not the only pokemon that will appear on his tile, so you have to make sure you fish every tile of the lake about 5 times just to make sure you didn't get unlucky
