Swordtail Fry Growth Rate

By Nadine Oraby | 2020 Update

When it comes to swordtail growth rates, one can easily get lost in the plethora of opinions available at first glance.

So, how fast do swordtail fry grow? Swordtail fry become fully grown adults in approximately 2 years. However, they can become sexually active and begin mating by as early as 3 months after birth. Fully grown swordtail males can reach over 6 inches in length whereas females can grow up to approximately 5.5 inches long.

However, there are several other factors one must be mindful of that can greatly influence swordtail fry growth rate.

How to Help Your Swordtail Fry Grow

Swordtail fish are, generally speaking, slow growing fish so it is best to try to do all you can to encourage their growth. There are a number of things that can stunt or encourage your swordtail fry’s growth during the first 2 years until it becomes a fully-grown adult. These include the size of the tank they are housed in, water conditions in the tank, and their diet.

Swordtail fish are relatively large tropical fish and, as such, require relatively larger tanks as well. A 29-gallon tank is a minimum for swordtail fish and bigger is always better. A 29-gallon tank is recommended when there is a smaller number of fish and you do not plan to breed them. Get a larger tank, depending upon the number of fry you wish to keep, where you can isolate your fry to grow safely as the adults will eat the baby swordtails. If the fry are not provided with ample space, it can stunt their growth and keep them from reaching their maximum potential size.

Tank conditions for swordtails

Swordtail fish are a freshwater species, so they thrive in conditions which mimic their natural habitat as closely as possible. Here are the best possible conditions for your swordtails:

  • Minimum tank size: 29 Gallons (132 Litres) for about 5-6 swordtails
  • Temperature: 72-78°F (21-28°C) while 75°F is ideal
  • pH: 7-8 (moderately alkaline
  • Hardness: 10-15 DH (moderately hard to hard)

Keep the water conditions as close to this as possible and your swordtails will flourish and grow happily. Invest in a good filter for your tank and, if you can, over-filter your tank. The swordtails will enjoy the current that it will provide as it closely mimics their natural freshwater habitat.

Swordtails, especially the fry, need decorations and plants to hide from the others. Place natural vegetation in the tank including floating ones to provide them safe haven from the other fish. Place thick vegetation on the tank floor, especially the surface. Like many fish, swordtails are able to jump quite far so keep the tank covered at all times to prevent them from jumping out and dying.

4 Tips to Make Fry Grow Faster (Video)

Diet for swordtail fry

Swordtails are omnivores which, in their natural environment, feed on invertebrates, insects, plants, and algae. A balanced diet which can mimic their natural one is essential for excellent growth, health, and even colour vibrancy. Try to provide them with high-quality food as cheap artificial food from any old pet store can lead to illness and disease.

Swordtail fry love newly-hatched brine shrimp and liquid fry. They should be fed as much protein and live meat as possible for maximum growth. Other live foods include bloodworms, mosquito larvae, and daphnia. Be careful with live food since any diseases they carry can be easily transferred to the fish.

Additionally, you can also feed them small pieces of yolk from a boiled egg. Crush it up and drop small pieces into the tank. Balance all this out with enough vegetation in the diet of your baby swordtails. You should feed them finely crushed fish flakes with vegetable supplements and spirulina to diversify their diet. Fry tend to eat in small portions and will feed quite often, so be sure to feed them frequently enough. Feed them in small portions multiple times a day but refrain from over-feeding them. Fish will often keep eating as long as you feed them. A good way to get past this issue is to feed them enough food which can be consumed within 3-5 minutes.

Swordtail Breeding and Reproduction Rate

Swordtail females come of healthy age for breeding at 6 months but can begin breeding as early as 3 months. It is recommended to wait until they are at least 6 months old as spawning is extremely taxing on the females and can lead to deterioration of health and even premature death.

Once impregnated, a female can take 28-30 days to spawn. Females can store sperm from a male and use it to reproduce again and again within a 6 month span. Females can give birth again 4-6 weeks after they last spawned. If you have bought a female swordtail fish that has been around males for any period of time, expect pregnancies. For these reasons, it is important to regulate and control breeding to avoid overpopulating the tank.

Caring for Newly Born Fry

Swordtails are known for eating their fry. In their natural freshwater habitat, swordtail fish never get to see their fry as the water current carries them away the moment they are born. It seems this has eliminated the ‘nurture’ trait amongst the parents and, as such, in the tank, the parents mistake them for food instead of offspring. If left unattended after a birth, the adults will eat most or all of the fry. In such cases, usually only 3 or 4 are left surviving from the brood at best. If you wish to keep the parents with the fry, place a large number of plants and decorations in the tank for the fry to hide in. Avoid cleaning the gravel during this time since fry could be hiding in it.

However, if you would like to protect and grow all the fry without the parents, invest in a depositing hopper. Place the female in it once you start seeing the gravid spot as this means she is close to spawning. The gravid spot looks like a dark spot on the underside of the female’s belly; this is caused by the eyes of the fry pressing up against the female’s scales. Spawning is said to usually occur in the morning. Once the female gives birth, the fry will drop through a slit at the bottom of the hopper and not come in contact with the parent or other fish. Then move the fry to a separate tank to grow freely. Wait until the fry are too large for the adults to eat and then reintroduce them back into the tank, if you wish to do so.

Sexing the Developing Fry

It is important to sex and separate your fry as early as possible to control breeding as well as ensure it does not start too early. You can determine their gender by looking at their anal fins – also called the gonopodium in males – located on the underside of the fish. Males will have a longer, more pointed anal fin (gonopodium) whereas females will have a more rounded, fan-shaped one. If you separate the males from the females, the former would get stressed out and fight for dominance.

Once the fry are 6 months old, you can begin breeding them for more fry. Keep 3 or more females for 1 male as this counts as a healthy gender ration.

Swordtail Lifespan

Swordtail fish enjoy a relatively long lifespan if provided the right conditions with a healthy diet. They can live up to at least 3-5 years. However, there are many reports of them living even longer than that. Swordtails are moderately easy to care for. Provide a large-enough tank with the right conditions, a balanced diet, prevent any aggression between them and your swordtails will live a long and happy life. Maintaining the right conditions while the fry are growing will also ensure that they grow up to have vibrant, bright colours to liven up your tank.

Related Questions

How can I clean my tank without killing the fry? This is a task that requires utmost care and patience. Remove as many of the fry as you can to a separate, temporary container and be sure to check around vegetation and decorations as well and then continue on to cleaning. Do not vacuum the gravel as fry often use it as a hiding spot. However, if you absolutely have to, do so with extreme care.

How can I make the fry grow faster? Provide the fry with lots of space by keeping them in a large-enough tank, clean water with moderate hardness, and lots of live food. This will help them grow much faster and healthier while also ensuring brighter colouring. Do not keep fry in traps during their growth stage since it will be nowhere near enough space for them to comfortably increase in size. This might stunt their growth.

When can I sell the fry? This depends upon the buyer, so be sure to look around for options. Usually, fish stores buy fry when they are more than 2 inches long. Ask the pet store or buyer what size they want the swordtail to be and then sell the fry to them once they’ve attained that size.

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