Winning a goldfish as a prize at a carnival can add an unexpected member to the family without time for preparation. Luckily, the hardy fish can live in a bowl for a few days while you set up a filtered aquarium for it to thrive in the long term. You won't even need to run to the store for goldfish food because the omnivorous fish will appreciate many of the foods you probably have on hand.
What do goldfish eat?
That famous yellow tin of goldfish food provides a convenient way to feed your omnivorous fish, but your goldfish will be happier if you mix fresh foods into his diet. In the wild, goldfish munch on aquatic plants, bugs, small crustaceans, and even smaller fish. In their natural environment, goldfish can grow to 18 inches long, with adult fish feasting on frogs, newts, and other small creatures in their environment.
Human food for goldfish
It's not much trouble to prep a dinner for a goldfish that she'll find delicious. It can also rival or exceed the nutrition found in the goldfish flakes. Raid the fridge to find appropriate vegetables for goldfish: a cooked pea with the shell removed, a blanched romaine lettuce leaf, cucumber, kale, spinach, or bits of cooked vegetables. Although a high-fat, low-fiber goldfish pellet should make up the base of a proper goldfish diet, adding fresh food on a regular basis provides optimal nutrition.
Pet food for goldfish
If you keep reptiles or amphibians as pets, you might have something on hand that your goldfish will enjoy. Toss in a few fresh, frozen, or freeze-dried brine shrimp, mealworms, or crickets. Goldfish will also eat earthworms, waxworms, bloodworms, blackworms, and daphnia. These animal-based foods will give your fish added nutrition and enjoyment once you have him on a pelleted goldfish diet. Goldfish living outside in a pond where temperatures fluctuate will especially relish these natural, high-value foods.
Choosing a goldfish food
It's easy to grab a yellow can of flakes in the pet aisle of the grocery store, but that's not what's best for your goldfish. Flakes often contain fillers and start decomposing the minute they hit the water, which means all those little bits contribute to a cloudy tank you'll need to clean sooner than later. Sinking goldfish pellets can be a good option, as goldfish tend to forage through the gravel for food. They can also be easily added to an automatic fish feeder. Gel goldfish food is good for fancy goldfish that have frequent digestive issues due to modified bodies, as it prevents constipation because of its high moisture content.
Don't let him overeat
Goldfish can be appreciative eaters, consuming all that you're willing to feed them. It's in their nature to try to store fat when food is available. However, when goldfish overeat and fat forms around their organs, they easily develop swim bladder disease where they can't maintain their uprightness or depth in the water. Give your fish only enough pellets as he will eat in 30 seconds and supplement with round-the-clock access to fibrous vegetables such as lettuce, spinach, or kale.
Clean up after dinner
Any food left in the aquarium that your fish doesn't eat will start to rot and cause water quality issues. Poor water quality is the most common cause of any fish disease, so daily remove bits of fresh food or leftover pellets with a net or aquarium forceps. Follow a regular cleaning schedule, including regularly replacing one-third of the aquarium water.
Growing big and strong
If you're eager to see your goldfish reach maximum size, feeding her too much won't get her there. Instead, make sure your fish has plenty of room to swim and she'll grow into it. Carnival goldfish can grow up to 10 pounds and up to 2 feet long, so a 40-gallon tank for one fish, along with appropriate water quality and a diet that is carefully monitored are what it takes to reach those proportions. For a second goldfish, increase the tank size by an additional 20 gallons. Keep in mind that well cared for goldfish can live in excess of 40 years.