"like a duck takes to water" vs "like a fish takes to water"

I am aware of the idiom like a fish out of water. What intrigued me is an article using like a fish takes to water.

Teo Zhen Ren, the swimming sensation from Singapore, took to swimming like a fish takes to water.

Is like a fish takes to water a valid usage? Is it an idiom? I thought the usual phrase was like a duck takes to water.

Solution 1:

Like a duck takes to water is a well known idiom, and has references in appropriate reference materials (e.g. books on idioms). Here, that and more duck idioms are discussed. As you've stated, it means easily.

However, googling like a fish takes to water gets many hits, where it's used exactly like like a duck takes to water. However, they are blog sites; there are no idiom explanations.

I suspect people use it because mixing of metaphors occurred somewhere along the line.

Fish idioms include: like a fish out of water, swims like a fish, drinks like a fish, and others.

Solution 2:

Like a fish takes to water

is valid, but not right. The "took to water" part suggests they weren't always in the water. Better (I believe) is:

He took to [his new job / skiing / living in Spain / other activity] like a duck to water.

However, your particular example is essentially the only place your phrase is used - when that activity is swimming.

Solution 3:

The correct idiom is "Take to something like a duck to water": (from TFD)

to learn how to do something very quickly and to enjoy doing it
    Sue just took to motherhood like a duck to water.
    He's taken to his new school like a duck to water.

Like a fish takes to water appears to be a variant of the original saying.

Solution 4:

I am a non-native speaker and I frequently hear such idiomatic constructions. Probably, the writer assumed that since both duck and fish take to water equally, they could be interchanged.

Solution 5:

It seems to me more likely that the intended fish/water reference above is to the expression "like a fish in water," as in this quotation from a letter by Daniel Baker, from Port Lavaca, Texas, on June 26, 1848, reprinted in The Life and Labours of the Rev. Daniel Baker D.D.: Pastor and Evangelist (1858):

O, it is pleasant to preach to a people who seem to be so eager to hear the word of life. It rouses me delightfully, and I feel as if I was in my own native element ; or, as the saying is, like a fish in water. I do believe I was cut out for a missionary — no mistake.