Lexicon: A
Ascorbic acid
Vitamin C; strong reducing agent, radical scavenger - protects other compounds from oxidation. The salts are called ascorbates.
Scurvy as a typical ascorbic acid deficiency disease is caused by collagen degradation, but practically no longer occurs today.
Almost all animals, with the exception of primates (apes, humans) and guinea pigs, can synthesise ascorbic acid themselves. I do not know whether this also applies to fish. If this is the case, further supplementation with vitamin supplements would be superfluous at best.