The Fishing Tourney is a special event that occurs in the Animal Crossing series. In Animal Crossing for the GameCube, it takes place on every Sunday of June for the Summer Fishing Tourney and every Sunday of November for the Fall Fishing Tourney. In Animal Crossing: Wild World for the Nintendo DS, it will occur on every third Sunday of January, March, May, November and December at 12:00pm–6:00pm and every fourth Sunday in February, April and October. As you can see the fishing tourney is much more frequent in Wild World. It also appears in Animal Crossing: City Folk.
In all three games, the goal of the Fishing Tourney is to collect the biggest fish. In the original, only bass will do. However, in Wild World and City Folk, all types of fish are acceptable. Rare fish can be very large, though usually a Sea Bass will do just fine. In Animal Crossing and City Folk, Chip the beaver will hold the contest, while Tortimer the mayor will do so in Wild World. In Animal Crossing, Tortimer will give you an Angler or Fishing (depending on if it's June or November) Trophy just for participating, however in order to get the fish trophy in Wild World and City Folk you'll actually have to win the competition. Also in City Folk, it seems that Chip wants you to catch the fish so that he can eat them, because he does just that after measuring a fish.