Im not sure.. but can this be it?
Down in the meadow in a little bitty pool
Were three little fishes and their mommy fishy too
Swim! said the mommy fishy, Swim if you can!
And they swam and they swam right over the dam
cho: Boop boop dittum dattum wattum, choo (3x)
And they swam and they swam all over the dam (repeats last line)
Stop! said the mommy fishy, You'll get lost!
But the three little fishes didn't want to be bossed
So the three little fishes set off on a spree
And they swam and they swam right out to the sea
Whee yelled the fishes, oh here's a lot of fun.
Swim in the sea 'til the day is done
So they swam and they swam, it was all, a lark.
'Til all of a sudden they saw a shark.
Whoa(?) cried the fishes, oh look at the whales
Quick as they could they turned on their tails
Back to the pool in the meadow they swam
And swam and swam back over the dam.