How to Take Care of Swordtail Fry?

Swordtails are live-bearing fish which can give birth to 10-100 fry at a time! Taking care of baby swordtail fish is the duty of the owner as the parent fish has no maternal instincts for its young ones.

So, how to take care of swordtail fry? You must get a separate tank for fry if you want to keep them safe from adult fish. If you cannot keep them in isolation, then you can install plants or aquarium accessories inside the tank where the fry can hide. The tank conditions for fry are the same as those for adult swordtails. They should be fed liquid or powdered food until they grow up.

Now, we’ll discuss all the nuances on how to take excellent care of your baby swordtail fish.

Swordtail breeding

Swordtail fish is ready to breed when it is 3 months old. If you do not want them to reproduce, then you must keep the male and female separate, otherwise, they would mate. Identifying male and female swordtails is not very hard as the male possesses a long pointed anal fin (the “sword”) called Gonopodium while the female has a fan-shaped anal fin.

However, you do not have to execute any additional effort when you want your swordtails to breed. After breeding, the gestation period lasts for almost 28 days. The pregnant fish will develop a large belly over time and a gravid spot will appear near her anal fin.

Care for pregnant swordtails

The pregnant fish doesn’t exhibit any mood swings, but it needs ideal tank conditions for good health. When the fish is close to giving birth, you should move it to a separate tank where it can deliver the fry smoothly. Male fish are a threat to pregnant females as they can get aggressive towards them which would lead to stress in the mother swordtail.

You should also avoid keeping the pregnant swordtail inside a breeding trap as it is very congested and there is not enough space to move freely. That can also create problems for pregnant fish which might result in the early birth of fry or abortion.

When is the swordtail fish ready to give birth?

Some beginner aquarists have no idea when the swordtails are ready to give birth so they can move it to a separate tank. Well, that’s very easy to figure out if you know what you’re looking for. If the pregnant fish starts showing any of the following behavior or signs, then it is time to move it to an isolated tank:

  • Stops eating
  • Slows down/stops swimming
  • Sinks to the gravel or stays in the same spot for a long period of time

Once the fish has given birth, you can immediately move it back to the community tank, otherwise it might eat her own babies.

Ideal care for the swordtail fry

There are many factors that you must bear in mind for the proper care of fry. These include:

  • Ideal tank size and conditions
  • Food for swordtail fry
  • Resting time for fry

4 Tips to Make Fry Grow Faster (Video)

Ideal tank size and conditions

The tank size must be large enough to accommodate all the fish easily. Swordtails are very active and social. They swim around the tank frequently unless they are sick or about to give birth. For one pair of swordtails, a 15-gallon tank is ideal, although the tank size must be upgraded if their fry are to live in the same tank

The tank conditions for fry are almost the same as for adult swordtails. These include:

  • Temperature: 72-82 degrees Fahrenheit
  • pH: 6.8-8
  • Water hardness: 1-24 DH
  • Ammonia levels: 0 ppm
  • Nitrite levels: 0 ppm
  • Nitrate levels: below 50 ppm

Food for swordtail fry

The fry are able to eat as soon as they are born. They cannot eat and digest adult food initially. So, you can feed them with liquid food that is easily available at any pet store. Other than that, you can feed them powdered fish flakes (ground to about the quarter of your pinky nail’s size) or live worms.

You can also grind boiled egg yolk in powdered form and fed it to the fry. It provides a variety of minerals and nutrients to them.

Swordtails grow very slow and if you want to speed up the process, then maintain perfect water conditions and feed them a good portion of meat (live worms or protein). For fry, the best food is baby brine shrimp or micro-worms which ensure their optimum growth.

Resting time for fry

It is very important for swordtail fry to take rest and sleep for proper growth and body functioning. Turn off the aquarium lights for almost 6-8 hours a day so the fry can sleep in a peaceful environment.

But make sure that you do not overdo this as the aquarium lights are necessary for fry because the light rays save them from the risk of deformities during physical development.

Hazards for swordtail fry

Let’s find out about the possible threats that a swordtail fry can face while growing up. These are the most popular reasons why a fry might die unexpectedly.

  • It becomes the prey of the adult fish in the tank
  • Due to toxic water

i) Adult fish as a potential threat to fry

The parent swordtails do not have any maternal instinct. In fact, they would eat their own child without the slightest bit of guilt. That means the biggest threat to baby swordtails are the bigger fish in their tank.

There are some tried and tested ways to protect the fry from big and hungry fish:

  • Keep the fry in a separate tank until they grow up. They will grow big enough in 2 months as to not fit in the adult fish’s mouth. At this time, you should return the fry back to the community tank.
  • Install plants in the aquarium if you are going to keep the fry with the parents and other adult fish.  The preferable plants to keep inside the tank are bushy or dense plants. Java moss is explicitly known for providing refuge to little fry.  Stones and aquarium toys are also good hiding places.
  • The mother swordtail can eat her own babies, so keep her well-fed to avoid such circumstances. It is recommended to feed a pregnant fish twice a day.

 ii) Toxic water

Fry are very sensitive to water conditions. The increased level of ammonia, nitrite or nitrate in tank water may cause the death of fry. Even if the aquarium is cycled to eliminate the ammonia, you need to change the tank water weekly to maintain the nitrate level. The baby swordtails can die due to high nitrate levels of the tank water if it is not changed regularly.

Clean water conditions will help the fry in growing rapidly and healthy.

To prevent toxins and chemical hazards from accumulating in the tank water, you must:

  • Change 25% of the tank water weekly
  • Before moving the pregnant fish to the new tank, complete the aquarium cycle (also known as the Nitrogen Cycle) once so that the babies are born into toxin-free and safe water

How to prevent your fry from dying?

To make sure that your fry stays healthy and alive, follow these instructions:

  • Keep track of the water parameters, so you can prevent any complications and react fastly when faced with unusual water conditions.
  • Feed them with care and provide them an ideal mix of vegetation and proteins.
  • Do not overfeed them and remove the excess food from the tank once they are done eating.
  • Always go for a larger tank size whenever you have the chance. Overcrowding increases the risk of stress which may cause the fry to die.
  • The fry can get stuck and die in the aquarium filter if they are not covered. Use sponge filters to keep the baby fish out of danger.

Related questions

What is the best age for swordtail to breed? A swordtail fish can start breeding usually around 3 months of age. But since they grow up slow, that’s why the generally accepted “healthy” age for them to breed is six months old.

My female is not getting pregnant, what to do? First of all, make sure that you have both male and female fish inside the tank. If the adult female swordtail is not getting pregnant in the presence of males, then you need to check the water parameters. Slightly warm water can increase the chances of mating between your swordtails. If you provide clean tank water and healthy food to the fish, it will start reproducing soon.

When can you shift the baby fish back in the community tank? You can move the fry back with the adults when they are reasonably big in size to protect themselves. Usually, when fry are 1.5-2 months old, they are large enough as to not fit into the mouth of adults and are able to survive with bigger fish in the community tank. If you introduce the fry back into the community tank and immediately see aggression on part of the adults, you should be proactive and isolate the fry again; better safe than sorry!


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1 thought on “How to Take Care of Swordtail Fry?”

  1. I need to know how often to feed 2 week old sword tail fry. I have 35 of them in a small tank at this time. Want to give them the best advantage to grow. Will move to a larger tank soon.


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