“What do fish need to stay healthy?”/“Vitamin Sea.”

“Vitamin Sea” is a fish pun for “Vitamin C.” “Vitamin Sea” has been cited in print since at least 1938.
   
“Vitamin Sea” riddles have been cited in print since at least the 1990s. This is from the Los Angeles (CA) Times on November 3, 1999:
   
Q: What does the fish eat to stay alive?
A: Vitamin sea.
   
“Coffee & Vitamin Sea are food for the soul” is another “Vitamin Sea” saying.
     
       
Wikipedia: Vitamin C
Vitamin C, also known as ascorbic acid and L-ascorbic acid, is a vitamin found in food and used as a dietary supplement. The disease scurvy is prevented and treated with vitamin C containing foods or dietary supplements. Evidence does not support use in the general population for the prevention of the common cold. There is, however, some evidence that regular use may shorten the length of colds. It is unclear if supplementation affects the risk of cancer, heart disease, or dementia. It may be taken by mouth or by injection.
     
4 August 1938, Manchester (UK) Guardian, “Vitamins for the Fish:Biscay Water for the Zoo Aquarium,” pg. 15, col. 7:
Having provided “vitamin sea,” the officials have an equally serious problem in the choice of foods.
     
Google Books
Best Riddle Book Ever
By Charles Keller  
New York, NY: Sterling Publishing Company, Inc.
1997
Pg. 36:
What do you take for motion sickness on a cruise?
Vitamin sea.
   
3 November 1999, Los Angeles (CA) Times, “The Kids’ Reading Room; Pint-Sized Punch Lines,” pg. E9, col. 3:
What does the fish eat to stay alive? Vitamin sea. (Candice, 8, Los Robles Academy, Hacienda Heights)
 
Google Groups: alt.teens.penpals
Pumping Iron.
merry mcgrath
11/5/99
What do fish take to lift weights?  Vitamin ‘Sea.’
   
30 November 1999, Los Angeles (CA) Times, “The Kids’ Reading Room; Jokes & Riddles,” pg. E7, col. 1:
What kind of vitamin does a fish like? Vitamin sea. (Andrew, 9, Visitation School, Westchester)
   
Google Books
August 2000, Boys’ Life, “Think & Grin,” pg. 65, col. 1:
Chuck: What kind of vitamin do fish need to live?
Buck: What?
Chuck: Vitamin sea. — Matt Boulden, Fairfield, Calif.
 
Twitter
Andrew ★ Brechin‏
@AndrewBrechin
Fish is good for you, as it’s rich in vitamin sea
4:40 PM - 21 Sep 2009
   
Twitter
Jack Leblond‏
@JackLeblond
What do you give a fish with a cold?  Vitamin sea!
7:13 PM - 28 Oct 2009
 
Twitter
CharStearns‏
@CharStearns
What do fish take to stay healthy?! Vitamin sea.
1:39 PM - 8 Jan 2010
 
Google Books
Jokes For Kids 2
By Peter Crumpton
PeteyRF Creative
2015
Pg. ?:
What do fish take to stay healthy?
Vitamin sea.
 
Google Books
Funny Jokes and Riddles for Children
By Alexandra Cooper
Lulu Press (Lulu.com)
2016
Pg. ?:
What do fish take to stay healthy?
Vitamin sea.
 
Twitter
Dad Jokes‏
@Dadsaysjokes
What do fish need to stay healthy? Vitamin Sea…
3:46 PM - 28 Nov 2017