Three fishermen are out fishing together and they each bring their own bucket. The buckets are identical, the only difference is the label on the bucket. The buckets are labeled "Salmon", "Trout", and "Salmon and Trout" and correspond to the fishing preference of each fisherman. Shortly after coming ashore, one of the fishermen realizes that they each put their fish in the wrong bucket when they were fishing, means all three buckets were now labeled incorrectly! Naturally, the lids of the buckets are all closed now.,How many bucket lids need to be opened and how many fish need to be taken out at random in order to properly label the buckets?



One lid only.
This is how:

1. Open the one called "Trout". It will never be trout, since all are labelled incorrectly. So it either contains Salmon or both Salmon and Trout.
2. If "Trout" contains Salmon, then Salmon contains Salmon and Trout"and "Salmon and Trout" contains Salmon all are labelled wrong. Else, it's the other way round.