Lyrics: A great song for hand motions and movement, and we like to use puppets, too. 
Try making "googley eyes" on the chorus, and then pretend that you are each of the animals in the verses.  Go underwater at the end!

(Chorus:)
At the 'quarium, the 'quarium
All the fishes make the googley eys and starium
And the other little fishes come and marry 'em
At the 'quarium, where we can go.

Oh, the shark, shark, shark goes a-swimming in the dark
He’s ferocious and he’s hungry every day
In the foaming ocean tide, little fishes run and hide
'Till the great big shark will swim away.

(Chorus)

There’s a little bitty clam, and he’s sitting on the sand,
and sits there every single day
And he doesn’t wink an eye at the fishes swimming by,
and he doesn’t have a single thing to say (Imagine that!)

(Chorus)

Oh, the octopus’s charms are its long and slender arms
They’re as long and they’re as sticky as can be
And the octopus’s fun is to hug its honey-bun,
but I don’t believe I’d like it done to me (Yuck!)

(Chorus)

Oh, the swordfish has a sword that would stick right through a board
So he swims just about wherever he pleases
Who would ever have supposed, he’d have a sword instead of a nose?
Makes you wonder what he does whenever he sneezes (Ahh-choo!)

("Underwater" Chorus)
At the 'quarium, where we can go.
At the 'quarium, where we can go!