Will Swordtails Eat Their Fry?

By Nadine Oraby | 2020 Update

Do swordtail fish eat their fry? They sure, do! Like most live-bearers, swordtails lack maternal instincts, therefore, they will gobble down their young ones without any hesitation. To save the fry, you would either need to provide the baby fish with a separate aquarium or install plants in the community aquarium.

Swordtail fish are complex creatures and several measures need to be taken to ensure the safety of baby swordtail fish. This article sketches out all the important points for swordtail fry care.

Do Swordtails eat their fry? (Video)

Adult Swordtails will eat their fry!

Adult swordtails are notorious for eating their fry, therefore, until they are larger, they must be separated from the adults.

It is always safer to keep them separate from their parents rather than relying on plants to camouflage the baby fish.

One way to keep the adult fish separate from the baby fish is to use a breeding trap.

However, it increases their stress levels which can consequently result in early births.

Therefore, to prevent stressful conditions for the fish, either remove the parents or provide an adequate number of plants in the aquarium.

Each of the available measures has been thoroughly discussed so you can choose one that fits best for your fish.

Breeding trap

Breeding traps are available in pet stores at cheap rates.

The traps consist of plastic containers where you put the live-bearing pregnant swordtail in.

However, the female fish should not be put in the trap until she is about to give birth as isolating her can induce stress.

The breeding trap is separated into two compartments and floats in the aquarium.

The top compartment of the trap is for housing the pregnant female swordtail and the small space which is between the top and bottom compartment is for the fry to drop through the bottom compartment.

The mother cannot reach the baby fish in the bottom compartment.

Even though it is highly unlikely, and the baby fish usually do not, there is a possibility that the fry may swim back through this space into the top compartment.

So, once the female has finished giving birth to the baby fish, the mother has to be removed from the trap and placed back into the community tank. Moreover, the plastic piece which is used to separate the fry from the adult fish should be removed from the trap, so that the fry can be raised for a short time in the trap.

However, this is not an ideal place to raise the baby fish for a very long time as the water in the trap tends to become stagnant. The trap needs to be replaced with water from the aquarium on a regular basis if you do intend on raising the fry in there. Fry is very small; therefore, it is best to raise the fry in their own aquarium to avoid their escaping into the community tank.

A heavily planted tank

You should take some extra steps if you plan on keeping your swordtail fry. A heavily planted tank is a must if the parents are going to be kept with the fry in the same tank. Bushy and dense plants are the best plants to choose. Moreover, Java moss provides an excellent refuge, particularly for the newborn fry.

Remove all adult fish from the aquarium

After the fry have been born, you can remove all adult fish from the aquarium, it will alternatively protect the baby fish from the hungry adults. What is further beneficial for the baby fish is that this measure also reduces the amount of waste in the water.

How can you tell when a female swordtail is ready to give birth?

A female swordtail will begin to swell with the quickly growing fry in its belly once it has been impregnated. Moreover, a dark gravid spot appears near the anal fin and a massive increase in the belly size of the pregnant swordtail occurs. Therefore, you can easily tell if the female is pregnant. The dark gravid spot is actually from the eyes of the swordtail fry which are pressing against the scales of the mother.

Even if you keep the male and females separate, most female swordtails will be pregnant when you first get them. The female fish will usually have enough sperm stored inside of them if they have been kept around males for a long period of time for several pregnancies to occur.

So, when you purchase a female swordtail, always be prepared for fry if they had been kept with male fish at the pet store.

Breeding swordtails

Swordtails will normally breed on their own like most other live-bearers without any intervention from their owners. However, it is important to ensure the fact that a safe ratio of male and female swordtails is maintained in the tank.

If there are too many males in the tank, then the females can quickly become stressed, as the males will often harass the females with relentless mating attempts which can lead to illness.

Likewise, it is best not to keep many males together unless you have a very large aquarium. It is not uncommon for the males to fight over the females, therefore, it is best to keep the male to female ration in a smaller tank usually 1:3 or in some cases, even 1:4.

Feeding the baby fish

Baby fish accept most commercially available fry foods. However, they are not large enough, therefore, cannot accept regular flake food. Instead, you should grind the flakes into a powdered form and feed it to the swordtail fry.

Consider feeding the fry baby brine shrimp, micro worms and live foods if you want to raise the healthiest possible fry; these are all excellent choices.

Baby swordtail fish can easily become obese if they keep eating. Moreover, they do not like older food. Only enough food should be dropped which can be consumed by the swordtail fry within 3 minutes. If you plan on storing frozen food for your baby fish, then make sure the food has been defrosted before being fed to the fish to prevent hard food from being ingested.

Other related questions

What is the ideal tank size for swordtails? Swordtails should never be considered as a candidate for a 10-gallon tank since they are relatively large tropical fish. Swordtails need larger tanks as smaller ones might lead to potential illness and stunted growth. It is recommended for swordtails to be in an aquarium of 29 gallons, however, this is only if you don’t intend on breeding the swordtails and keeping the fry.

Is it absolutely necessary to provide live plants for your swordtails? Although it is not completely necessary, it is recommended to provide live plants for your swordtails. A heavily planted aquarium provides shade and cover for the fish, closely mimicking their natural habitat. Even though fake plants will also work, the dual benefits of oxygenating the water and improving water quality are not offered by fake plants.

What size filter should you choose for swordtails? Bigger is usually better when choosing a filter for swordtails. However, if that’s too hefty on the pocket for you, then you can substitute the need of an expensive filter by filtering your tank more regularly. Swordtails will enjoy the current an extra-filtered tank brings with it.


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