According to the American Pet Products Association (APPA), over 11 million American households have freshwater fish as pets 1 . Many people probably started with goldfish before graduating to tropical varieties. If you have both types, you might wonder if you can feed them the same diet. The short answer is that it won’t hurt them and isn’t toxic, but it isn’t recommended as a staple.
You shouldn’t feed goldfish tropical fish flakes because of the varying nutritional needs of the species. Goldfish have specific requirements, too, that put tropical fish flakes off the menu.
Nutritional Requirements of Goldfish
Scientific literature contains a lot of information about aquaculture species. Therefore, much is known about what different fish need for optimal health. Goldfish are part of the Cyprinidae family, which includes familiar species such as carp, minnows, and shiners. Knowing this information can provide valuable clues about what goldfish need. For successful rearing of goldfish, they require about 40% protein and 4.0 kcal /g energy in their diet. Fish kept in warmer temperatures have higher requirements.
Species vary in their protein needs, which can range from 25%–60% of their diet, but all need the same 10 amino acids. The protein percentage varies for each species’ diet. Carnivores require a greater amount than herbivores. Research on goldfish reveals that they fare best with around 40% protein. Fish fed diets higher in protein did not develop adverse signs, but didn’t show much improvement in terms of growth either.
Fats or Lipids
The problem with too much fat isn’t much different from that of any terrestrial animal, including humans. Obesity can occur with fish, too. However, the biomechanics of obesity are different in fish as they are cold blooded; fish fed a diet with the right amount of fats but kept in a temperature outside their normal range will not grow properly.
Unfortunately, there’s still more bad news about tropical fish flakes. We must also consider the role of carbohydrates, particularly starches. It’s all about balance. Too little can slow growth and can cause spontaneous diabetes in this fish family. There’s also a looming risk of obesity from too many carbs.
Other research has shown a high-carb diet can negatively affect growth in Wuchang Bream, a related species. This fish also had a higher mortality rate when overfed with a high starch diet during their growth phase.
Many goldfish die as a result of improper feeding, diet, and/or portion sizes – which can be easily prevented by proper education.
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Diet in the Wild
Let’s look at what goldfish eat in the wild compared to commercial diets. These fish are opportunistic omnivores in their native habitats. They’ll eat a variety of foodstuffs, including plants, insects, and crustaceans. This supports the theory that goldfish won’t thrive with a high-carb diet. Instead, they’ll do best with plenty of protein and fat.
The Problems With Tropical Fish Food
The main issue with tropical fish food is that it typically contains lower amounts of protein than what is required by goldfish. In addition, their formulation usually results in a lightweight product that floats for a long time before slowly sinking into the bottom of the tank, which isn’t ideal for goldfish. Goldfish that eat food from the top of the tank (while it’s floating) have a tendency to swallow a great deal of air while they do so, which may lead to or perpetuate swim bladder issues. This is why a sinking heavy pellet is best for them.
In addition, goldfish aren’t the best at picking up small flakes of flakes from the floor of an aquarium; pellets can easily get lodged between pieces of substrate, where they slowly dissolve and pollute the water.
Finally, the stronger filtration system in place in most goldfish tanks means that many light-weight flakes can be quickly siphoned away by the filter before goldfish (particularly the fancy variants) have an opportunity to eat them.
While you can offer your goldfish tropical fish flakes, we conclude that it’s not an ideal diet for the long term. The differences in the nutritional profiles of the various products are red flags and not a wise diet choice for goldfish. Instead, we recommend feeding your fish a product formulated for their species and unique dietary needs.
Other Goldfish Reads:
- Tropical Fish vs Goldfish: Which One Is Right for You?
- Can Goldfish See Color? Fact vs Fiction
- Make a Deep Sand Bed for Aquariums in 6 Easy Steps
Featured Image Credit: Dien, Shutterstock