I have ground up store vitamins in my homemade beef heart. I can't say if it did much but it definatly didn't hurt them. I have also used seachem reef vitamins as well
id be careful with human vitamins
not saying they are bad
but one pill might be over dose to a fish that only weighs afew ounces
not saying you feed a whole one though
ive read that zoos (this was from reading jurassic fish) put in afew pills in some fish before they feed the giant pirarucus.
but they dont know if it helps either