Do you believe that the only food goldfish need to thrive is goldfish flakes or pellets? Or have you ever seen daphnia or larvae that is sold in pet stores and wondered, "Should I give that to my goldfish? Why should they eat that?" After examining a variety of diets for goldfish, I've come to the conclusion: a large number of people are actually inadvertently harming their goldfish.
Here's why: In the wild, goldfish naturally get a varied diet: They eat algae, leaves, tadpoles or even insects; pretty much anything they can get eat! They are natural scavengers and omnivores (they eat everything).
However, in aquariums it is normal for owners to solely feed them man-made fish flakes.
These contain a mixture of vitamins, bulking agents and various dried foods.
They are not a balanced enough diet for goldfish to survive on.
Goldfish have a high need for fresh fruit, vegetables and variety in what they eat.
One the easiest and fastest ways that you can help your goldfish stay healthy is to give them extra vegetables.
This keeps their digestive tract clear.
What happens if you exclusively feed dried-food to goldfish? You can expect to see constipation-type problems that could result in so-called Swimbladder Disease.
This happens when your fish becomes constipated and causes it float to the surface and hang there - like a helium balloon stuck on the ceiling.
Since goldfish can't move, they often starve if this happens.
Here are my nine easy-to-apply tips for a healthy goldfish diet:

1. Only feed goldfish once a day
2. Feed goldfish vegetables and fruits regularly (every other day)
3. Once a week, give each fish 3 shelled peas, finely chopped
4. Try out small amounts of other fruits/vegetables
5. Give them a small amount of cooked and chopped carrot (it is cooked slightly, they will be able to eat it more easily)
6. You can also give a small amount of grated carrot to goldfish
7. Keep a note of the foods they enjoy (goldfish are like people and have their favourites!)
8. Monitor how your goldfish are doing: notice how healthy they are.
   If you notice them floating on the top of the tank, inflated like a balloon, then you need to take steps to deal with Swimbladder Disease
9. Only ever give larvae, brine shrimp or daphnia as occasional treats: they are protein-rich, and can cause constipation in goldfish

One last thing: don't be fooled.
Your goldfish will get used to you feeding them.
They will often come up and "look hungry" shortly after you've fed them.
You must absolutely get used to being disciplined and feeding them just once a day Feed your goldfish a varied diet, and you can expect them to be healthy and thrive.