Oh, a cowboy needs a horse, needs a horse, needs a horse,
And a cowboy needs a hat, needs a hat, needs a hat,
And he oughta have a rope, have a rope, have a rope,
If he wants to keep a-ridin'.

Now a cowboy needs some boots (fancy boots, fancy boots),
And a set of shiny spurs (shiny spurs, shiny spurs),
And he oughta have a song (have a song, have a song),
If he wants to keep a-ridin'.

Oh, the fence is long and the sun is hot,
And the good Lord knows that a cowboy's got
To keep (ridin', ridin' along).

Now if a cowboy's got a horse, and a hat, and a rope,
And a pair of fancy boots, shiny spurs, and a song,
Then there's very little else in this world that he needs
If he wants to keep a-ridin',
Ridin' along.

[Yodel.]"

See that list.. not a single mention of mermaids...

We can be fairly certain a cowboy does not need a mermaid...