What Foods Do Swordtails Eat?

Swordtails are omnivores who hunt and eat anything that fits into their mouths. They feed on aquatic invertebrates, insect larvae, tiny crustaceans, worms, algae, and even plant debris. That said, in aquarium settings, swordtails require a nutrient-rich balanced diet.

It’s rare to find a fish that’s both easy to care for and peaceful, which is why swordtails are so popular. They’re small freshwater tropical fish that can survive in a variety of environments and consume a wide range of foods.

In this post, we’ll lay out what swordtails eat in the wild and an aquarium. We’ll also go over foods to avoid feeding swordtails, as well as a proper feeding schedule to ensure optimal nutrition, so sit tight!

Orange Swordtail

What Foods Do Swordtails Eat?

Swordtails are both carnivorous and opportunistic eaters, which means they eat pretty much anything that fits in their mouths.

In the Wild

In the wild, swordtails have strong immune and digestive systems that allow these tiny fish to feed freely.

Here’s what swordtails often eat in the South American rivers:

  • Insects and insect larvae
  • Small aquatic invertebrates, such as daphnia, plankton, and plant debris
  • Algae and other vegetation
  • Dead fish
  • Crustaceans

In an Aquarium

The aquarium is a controlled environment that, no matter how favorable it is, won’t have all of the components necessary for the swordtails’ proper growth and development.

That’s why it’s on you to feed your fish a balanced diet of the following foods.

Commercial Food

Swordtail commercial food contains high-quality flakes and pellets. Both are often used to supplement live and frozen food and can be a staple in a swordtail’s diet.


A balanced swordtail diet should include vegetables, so you can feed swordtails cucumber medallions, zucchini medallions, shelled peas, and broccoli.

Before you offer the piece of veggie to the fish, you should blanch it in boiling water and allow it to cool first.

Alternatively, you can feed the fish algae wafers, which are packed with nutrients similar to the ones in cucumbers and zucchinis.

Live Food

For swordtails, live food is an excellent source of protein, which they require regularly.

Swordtails’ most favorite live foods include:

  • Blackworms
  • Blood worms
  • Daphnia
  • Brine shrimp
  • Mosquito larvae
  • Fruit flies

When you’re choosing live food, make sure they’re good quality because low-quality live food can transmit diseases and parasites to the fish.

It’s also worth noting that swordtails, like most livebearing fish, don’t have parental instincts, especially in aquarium settings. This characteristic explains why mother swordtails almost always eat their fry soon after birth.

That’s why, if you don’t want swordtail fry to become food for adult swordtails, it’s essential to separate the babies from their parents with a partition or to relocate them to a different aquarium until they become juveniles.

Frozen Food

Many live foods, such as brine shrimp and daphnia, are also available frozen. While the nutrients are virtually identical, frozen food is much easier to feed to the fish.

It also ensures that the swordtails don’t contract any diseases or parasites, which is a higher risk in live food.


Aquarists often use vitamins and algae-based supplements to provide swordtails with the nutrients that they would normally acquire in nature.

What Food Do Swordtail Fry Eat?

Swordtail fry search for food as soon as they’re out in the water. They need good-quality protein so that they maintain a healthy growth rate.

You can feed swordtail fry freshly hatched brine shrimp, baby fish food, and powdered fish flakes. You should also provide them with live meat as much as possible. Live meat includes bloodworms, daphnia, and mosquito larvae.

If you think the swordtail fry are getting bored with their current diet, you can feed them tiny pieces of crushed-up boiled egg yolk. You can also feed them spirulina to diversify their diet.

Keep in mind that feeding low-quality food to swordtail fry is just as bad as feeding it to adult swordtails. Low-quality food can slow the fry’s growth rate and harm their health.

What You Shouldn’t Feed Your Swordtails

There’s no doubt that swordtails can eat a wide variety of foods. Still, they can’t eat everything due to their sensitive stomachs.

Let’s take a look at foods you shouldn’t offer to swordtails and swordtail fry.

Gluten and Yeast

Gluten-containing foods contain nutrients that swordtails can’t digest. Swordtails may become constipated, bloated, have a lower metabolism, and even become poisoned if they consume gluten-containing foods.

So, it’s vital for their health that you don’t offer them any gluten-rich foods.

Gluten-containing foods can also contaminate aquarium water. Any leftover food will not only clog the filter but will also emit ammonia as it decomposes.

The poor water quality and ammonia buildup can cause extreme water toxicity, which is extremely life-threatening for swordtails and any other fish in the aquarium.


Swordtails won’t reject a sugary treat, but foods high in sugar are a big no-no in aquariums. To begin with, microorganisms such as yeast and bacteria feed on sugar, which can help them proliferate.

You don’t want these microorganisms to increase because they reduce oxygen levels and produce toxic substances like carbon dioxide, alcohol, and lactic acid.

What’s more, because sugar is osmotic, it can draw all of the water from the swordtails and plants in an aquarium, leading to dehydration.

High Protein

While swordtails need protein in their diets, they can’t digest high-protein foods, such as worms and shrimp.

Swordtails may become constipated or sick if they consume too much of those high-protein foods, which may cause them to lose their appetite.

How Often Should You Feed Swordtails?

It’s easy to overfeed most fish, including swordtails, because they don’t always know when to stop eating. As a result, the fish will continue to eat

What’s more, in case the fish do end up leaving leftovers, the aquarium’s water quality can decline over time.

That’s why you should feed your swordtails on a schedule to ensure that they aren’t so full that they don’t finish the food and leave leftovers.

Adult swordtails need to be fed small portions two to three times a day. Swordtail fry, on the other hand, eat even smaller portions and more frequently than adult swordtails.

Just make sure you regularly change the water to maintain good water quality and prevent infections, diseases, or parasites

In Conclusion

One of the reasons aquarists and people, in general, enjoy raising swordtails is that they’re not picky eaters. In the wild, these tiny tropical fish can feed on anything, from insects and crustaceans to algae.

On the other hand, in an aquarium, swordtails’ diet depends on what you provide them. You can feed your swordtails and their fry a variety of foods, including daphnia, blanched vegetables, and egg yolks.

You can even provide the fish with vitamin and algae-based supplements to ensure they get all the nutrients they need.

As long as you feed your swordtails a varied and balanced diet, they should grow, thrive, and stay well-nourished.