According to the American Pet Products Association (APPA), 11.8 million American households have freshwater fish as pets. 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 in the short term, 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. For example, you might be giving shrimp or bloodworms to the carnivores in your tank. 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.
These fish are native to many temperate and continental climates around the world, including North America, Eurasia, and Africa. They also don’t have stomachs. Undoubtedly, all these factors will play a role in the nutritional requirements of goldfish.
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 at least 29% protein.
We looked at the nutritional information of several brands of tropical fish flakes. Every product we surveyed contained more than 40%. The earlier cited study also considered the effects of a high-protein diet on fish weight. While the specimens fed more protein initially gained weight, the results leveled out toward completion. The researchers postulated that fish probably metabolized the excess.
The takeaway is that there aren’t clear health benefits to feeding goldfish more protein. However, that’s not the whole story.
Fats or Lipids
The same study also looked at the fat content of various foods. The problem with too much fat isn’t much different from that of any terrestrial animal, including humans. Obesity can occur with fish, too. It can also cause fatty liver disease. Researchers concluded that 13% fat was the optimal proportion. They extrapolated it to a protein-energy ratio of 9.7 kcal/g.
This figure is significant since a deviation from it can come at the cost of other vitamins and minerals essential for goldfish health. Most of the tropical fish flakes we surveyed contained 10% fat. It’s important to remember that fat isn’t always bad. It’s vital for absorbing fat-soluble vitamins, such as vitamins A, D, and E. Therefore, a risk of dietary deficiencies exists if you feed your goldfish this food.
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. However, too much 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 in low-oxygen conditions. As anyone who has raised goldfish will tell you, that’s not an uncommon occurrence.
The foods we researched didn’t list the percentage of carbohydrates, nor did the manufacturers’ websites. However, we can surmise that foods containing rice or other starches have a fair amount, especially if they’re listed high on the ingredient list.
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
Tropical fish often do well on flake diets in part because they’re used to this form. Flakes are appropriate for fry and smaller goldfish. However, pellets have the advantage for goldfish because they’re nutritionally dense. When flakes dissolve, the vitamins and minerals dissipate, too. There’s also the risk of fouling the water and stressing your fish.
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