This wasn't imagination, Doctor.

2 seconds sound clip from the Creature from the Black Lagoon (1954) movie soundboard.

You can hear this line at 00:41:13.730 in the Blu-ray version of the movie.

Quote context

[...]

- The kamongo was a fish that breathed air.

- What does that prove?

- Nothing. Except that the kamongo fish, which has lungs, exists today, right here in the Amazon. It hasn't changed in all these millions of years.

- That doesn't prove the possibility of a gill-man.

- If the evolution of that species could reach a dead end way back then, and still survive, why couldn't another?

- Where is he?

- I was sure I had him in my finder.

- For a merman, he takes a fine picture.

- This wasn't imagination, Doctor.

- I'm sorry, David.

- What proof do we have if we never find it again?

- If you hadn't stopped me, we could have taken it! Dead or alive, what's the difference?

- What happened?

- Chico!

- What happened?

- Chico! Chico is gone.

[...]