Why Are My Tadpoles Dying?

If you have a pond at home and you are looking to raise your own frogs all the way from tadpoles, you need to make sure that your tadpoles are in an environment that is conducive to survival.

While it is normal that not all tadpoles are going to survive into adulthood, there are some cases where there are more tadpoles dying than expected.

Generally, inappropriate food, improper water, lack of space, and illnesses can contribute to high mortality rates in tadpoles. Such conditions can lead to stunted growth, cannibalism, and high mortality rates in tadpoles.

Unlike small mammals, tadpoles tend to take care of themselves in the wild the moment they transform from their eggs.

However, if you have tadpoles in captivity, you need to care for them. You have to make sure that you provide living conditions that are conducive enough for the tadpoles to survive on their own.

I am going to cover the most common reasons for captive tadpoles dying and how you can easily adjust their living conditions to improve survival rates and have more tadpoles that turn into frogs.

1. Inappropriate Foods

As a general rule, tadpoles are herbivores from 0 to 6 weeks and are omnivores after 6 weeks until they become froglets. Wild tadpoles generally eat algae, moss, and phytoplankton, but they can eat boiled lettuce, spinach, and broccoli in captivity.

What Can Tadpoles Eat-min

During their early stages of development, tadpoles are herbivores and can safely eat leafy greens such as boiled and cooled broccoli, leeks, cabbage, watercress, spinach, kale, as well as egg yolk in captivity. They can also eat small insects such as aphids, and ants once they begin to develop legs.

This means that you should not be feeding your tadpoles all kinds of processed meats, fruits or any other foods that you regularly eat.

I cannot tell you the number of crazy things people feed tadpoles and then wonder why they are dying.

Sure, tadpoles may nibble on fish food, hot dogs, hoagies, bacon, bread, dog food, strawberries – but none of those things are good for them. Many of these foods are full of salt or sugar that will dehydrate them, or deteriorate their health.

Algae is the top food source for tadpoles in the wild. While they can still eat other types of greens, such as lettuce, cucumber, or watercress, thick greens like kale, algae, broccoli, spinach, and rapini should still be their primary food source.

A healthy tadpole diet needs to contain calcium since it is mineral for tadpoles development. As tadpoles metamorphose, their cartilage skeletons begin to ossify, creating a high demand for calcium (Stiffler, 1993).

Including calcium in tadpole diets is essential to improve their survival rates, reduce deformities, and reduce the risk of tadpoles contracting SLS (explained below).

However, too much oxalate or oxalic acid found in some of these vegetables, notably spinach, has been found to lead to renal tubular necrosis and death in developing tadpoles (Forzán et al., 2014).

Therefore, be sure to feed tadpoles a varied and balanced diet of plant-based foods, and animal-based foods during their herbivorous and omnivorous development stages.

Find a list of everything you can feed tadpoles on our blog

Feeding tadpoles the wrong foods can stunt their growth, lead to cannibalism, and unnecessary deaths.

So if you want your tadpoles to thrive, you need to feed them healthy leafy green vegetables and introduce insects once they begin to develop legs.

Do not feed them any processed foods, fruits, or meat.

2. Improper Water 

Captive tadpoles require cleaned filtered water with calcium chloride and magnesium sulfate, and a PH balance between 6.5 and 7.5 to be considered safe. Water should always be tested before introducing it to amphibians.

The type of water your tadpoles are living in can also affect mortality rates. That is because tadpoles and frogs alike simply cannot live in all types of water, notably saltwater.

Of course, this includes your common tap water. The water also needs to be oxygenated enough to ensure their survival.

What you need to know about tap water is that it is actually treated to make sure that it is clean enough for human consumption.

However, the same treatment process that tap water undergoes makes it unsafe for tadpoles.

As such, when you want to make sure your tadpoles survive, it is best to go with other types of water such as bottled, filtered, and distilled.

You can still use tap water but make sure that you boil it to remove any of the impurities that are unsafe for the tadpoles and then let the water cool to a temperature that is suitable for them.

However, you need to reintroduce minerals to this water. Tadpoles require calcium-enriched water and may not grow bone during metamorphosis if they lack the mineral.

Overfeeding can also lead to improper water. Therefore, be sure to feed tadpoles appropriate amounts of food and keep the water clean.

Find the best type of water for your tadpoles on our blog

It is also important that you make sure that your tadpoles are living in a pond or a tank that is clean enough for them to survive. Like any other water-based animal, tadpoles can easily get sick and die when the water they live in is dirty.

And when we say dirty, we are talking about murky and cloudy water. For example, if you feed them egg yolk, you need to be sure it is completely consumed and does not cloud the water.

Tadpole what eat-min
A Green Frog Tadpole I found in a local pond

Also, tadpoles should not be kept in water that is too cold or too hot for them. You need to make sure that the tadpoles are kept in a tank or a pond that is warm enough, but not in full sun.

If you are using a pond in the backyard, make sure that the pond is shaded but remains between 15°C and 25°C (59°F to 77°F). Cold water will slow down their rate of development, and hot water can kill them (CTNF).

Speaking of which, it is common for people to top off their frog ponds with hose water directly which contains chlorine and can be very hot (if the hose was in the sun) or very cold.

Always fill a bucket and leave the water in the shade for 48h to let the chlorine evaporate and to let the water hit ambient temperature before topping of your frog pond. This will avoid temperature shock in tadpoles and frogs which can lead to deaths.

Dumping very hot or very cold water into a pond containing tadpoles can cause them temperature shock which can lead to premature deaths.

3. Lack of Space

Tadpoles are known to turn to cannibalism when adequate food and space is lacking in their environment. Tadpoles require enough space to thrive with their siblings, or they will reduce the competition by eating the weakest tadpoles.

Make sure your pond is large enough to handle the amount of tadpoles it contains. When there are more tadpoles in a limited space, competition among the tadpoles will rise, especially when the food source and the space they need to grow into healthy frogs tend to be limited.

It is best to control the number of tadpoles that you want to raise to maximize the chances of each of these tadpoles growing into adult frogs.

If the tadpoles in your pond were not purchased and naturally occurred, you may be able to relocate some of them to their original habitat following local laws.

See how to relocate frog eggs and tadpoles on our blog

4. Tadpole Illnesses

Illnesses are also common among tadpoles. These illnesses can be passed on by carriers such as their parents (even though they do not show signs of the illnesses).

Such illnesses could also be due to poor sanitation or even hereditary factors.

According to a Cornell University study and other research carried out on the topic (cited below), here are some of the more common amphibian illnesses that tadpoles can also suffer from:

Batrachochytrium dendrobatidis (chytrid, or Bd)

  • Reddened skin
  • Lethargy and inappetence
  • Inability to remain upright
  • Thickening or excessive shedding of the skin
  • Restricted in larvae, post-metamorphic animals affected

Batrachochytrium salamandriivorans (salamander chytrid, or Bsal)

  • Reddened skin/lesions
  • Lethargy and inappetence
  • Not yet known to be in the United States

Ranavirus

  • Reddened skin/hemorrhages
  • Lethargy and inappetence
  • Bloated abdomen
  • Seen in larvae and adults
  • Not amphibian-specific
  • Virus-related sickness

Renal tubular necrosis

  • Not visible to the eye
  • Due to overfeeding oxalic acid (found in leafy greens)

Spindly leg syndrome (SLS)

  • Musculoskeletal abnormalities
  • Malformed joints
  • Reduced limbs
  • Shorter limbs
  • Thin muscle fiber in the limbs
  • Detached limbs
  • Due to lack of calcium in diet

More About What Tadpoles Need to Survive

While it is expected that not all tadpoles are going to survive from the dozens of eggs that the mother frog lays, it should be expected that there should still be a good number of survivors that grow up into frogs.

So, if you notice that more tadpoles are dying than expected, you might be wondering why that is so. In that regard, there are a few factors that we need to look at.

As a summary to this article, here is what you need to do to reduce tadpole mortality:

Learn more on our blog:

Common Questions About Tadpoles Dying

Why are my tadpoles not turning into frogs? Generally, inappropriate food, water, lack of space, and illnesses can contribute to high mortality rates in tadpoles. Such conditions can lead to stunted growth, cannibalisation, and high mortality rates in tadpoles. Tadpoles are expected to turn into froglets sometime between 12 and 16 weeks.

Sources

Cornell, Curious Case of Tadpole Mortality

Lassiter E, Garcés O, Higgins K, et al. Spindly leg syndrome in Atelopus varius is linked to environmental calcium and phosphate availability. PLoS One. 2020;15(6):e0235285. Published 2020 Jun 29. doi:10.1371/journal.pone.0235285

Forzán MJ, Ferguson LV, Smith TG. Calcium Oxalate, Nephrolithiasis and Tubular Necrosis in Recent Metamorphs of Rana sylvatica (Lithobates sylvaticus) Fed Spinach During the Premetamorphic (Tadpole) Stage. Veterinary Pathology. 2015;52(2):384-387. doi:10.1177/0300985814535607, 2014.

Stiffler DF. Amphibian calcium metabolism. J exp Biol. 1993;184: 47–61. Available: http://jeb.biologists.org/content/jexbio/184/1/47.full.pdf

Daniella Master Herpetologist

Daniella is a Master Herpetologist and the founder of toadsnfrogs.com, a website dedicated to educating the general population on frogs by meeting them where they are in their online Google Search. Daniella is passionate about frogs and put her digital marketing skills and teaching experience to good use by creating these helpful resources to encourage better education, understanding, and care for frogs.