Raising newt larvae|
Originally published in Coronella Vol. 1 (2006), No 1.
Female Cynops ensicauda
Nowadays a variety of newt species are kept in aquarium as pets. Many of the commonly kept species reproduce readily when kept properly. In this article I explain methods and techniques that I have used to raise newt larvae. I do concentrate especially on two species, Spanish Ribbed Newt (Pleurodeles waltl) and Sword-tailed Newt (Cynops ensicauda), but presented methods can, and have been applied to many other salamandrid species as well.
During last couple of years I have bred regularly two newt species. These species are Spanish Ribbed Newt (Pleurodeles waltl) and Sword-tailed Newt (Cynops ensicauda) from Japan. In this article I shortly present these two species and explain methods that I have used to breed them.
I have kept different salamanders and newts for over 15 years. Methods explained in this article are based mainly on my own experiences during these years, and these same methods are also recognized in current literature. However there are many different ways to do things right and it is often hard to find “the one right way”. One method might suit someone, but be totally inappropriate for someone else. Because of these reasons this article is not a “recipe for breeding newts”, but rather some notes of my personal experiences. I try to present different methods of doing various things, and explain pros and cons I have experienced with each of them. I hope that this way reader gets a wider look at this subject, and will be able to find the methods that are appropriate just for him/her.
Short introduction of the species
Both species dealt with this article are salamandrids, they belong to family Salamandridae.
Spanish Ribbed Newts are native to Spain and Portugal. They are large salamandrids that may reach total length of 30 cm. In captivity they usually remain much smaller, normal being 15-20 cm. They have flattened head, sturdy body and laterally compressed tail that is approximately as long as the body. Back is grey with greenish or yellowish tint. Belly is lighter, usually cream in colour. All over the body there are darker spots. Each flank has a row of tubercles. That is where newt may puncture its ribs through the skin. This is a defence mechanism that usually causes no, or only little harm to the newt. Ejection of the ribs rarely occurs in captive animals.
Male Ribbed Newt has a dark nuptial pad on its arm.
Ribbed Newts are almost totally aquatic, and they inhabit stagnant waters like ponds and irrigation systems. If water dries up, newts bury themselves to mud or hide under a stone where they are able to keep themselves moist during the dry season. For more information about Ribbed Newts, see for example Griffiths, 1996.
Sword-tailed Newt is native to Ryukyu Archipelago of Japan. Females may reach a total length of 16 cm. Males are bit smaller. Again, maximum lengths are rarely achieved in captivity, so in aquarium these newts usually are 9-13 cm long. These salamanders are typically newt-shaped, and their back is brown or almost black. The underside is usually yellow or orange with varying numbers of black dots or other patterns. Colour of the belly extends to the lower edge of the tail, and there may be lines or other patterns of same colour also on the back of the newt. Some newts (those belonging to subspecies C. e. popei) have small light dots, often referred as “golden dust”, on the dorsal and lateral parts of their body.
Sword-tailed Newts inhabit all kinds of stagnant and slowly moving waters. They may also spend periods of time living terrestrially in sub-tropical woodland habitats. For more information about this species, see Johnson, 2004.
Both species may be kept in aquatic and densely planted aquarium setup. Especially Sword-tailed Newts should be given an opportunity to rise from water to terrestrial environment. This can be done by ether placing a floating piece of cork on the surface, or by creating a terrace of land to other on of the aquarium. This kind of setup is known as aqua-terrarium. Also other methods of creating a land area are available, but these two are the ones I have found most suitable.
In this aqua-terrarium for Sword-tailed Newts there is a bank that shapes a small ground area.
If land area is big enough, some plants may be planted there to give some shelter on land. Plenty of aquatic plant should be planted in water area. In addition drift wood, stones and other elements may be used to decorate aquaria. For more ideas to decorate aquarium or aqua-terrarium, see for example Bjornebo, 2001.
As dwellings I use aquariums that are 128 litres (80 x 40 x 40 cm) in volume. I think that this size of aquarium is suitable for a pair of Ribbed Newts or 2-4 adult Sword-tailed Newts. Both species are quite lively, so even bigger dwelling is possible. A suitable depth of water is 20-30 cm for Ribbed Newts and 15-20 cm for Sword-tailed Newts. At the winter time (dry season) depth of water for Ribbed Newts may be lowered to 15 cm to simulate natural cycle of the seasons.
Water temperature should stay under 21 centigrades for Ribbed Newt and between 20 and 24 ºC for Sword-tailed Newts. At summer time room temperature easily rises in normal residence environment higher than this, even up to 30 ºC. It is not usually lethal for the newts, but should be avoided. At least temperature should drop down to normal room temperature at night. At winter time a cold period of 8 weeks is recommended. During the cold period temperature should drop 8-10 degrees from the summer temperatures. If you are able to offer natural kind of temperature cycle newts are more likely to start breeding. If kept on constant temperature all year long newts will very likely survive, but they might refuse to breed and it might shorten their lifespan.
I do highly recommend equipping aquarium with a proper sized filter and a lightning system based on fluorescent tubes. Filter and lightning are not absolute obligatory, but they will make maintenance a lot easier. In any case is necessary to do partial water changes and remove all loose organic waste (food, faeces est.) from aquarium regularly.
Newts are carnivores that consume all kinds of invertebrates. In aquarium diet usually consists of earthworms, snails, crustaceans, insects and their larvae. Food items may be alive or frozen. You may occasionally offer strips of lean beef, heart or fish. Food items may be offered directly to newts, or they might be spread on the bottom of the aquarium. If spread, take care that you don’t overfeed the animals. All food items must be consumed in 10 minutes. If any food remains uneaten it must be removed immediately before it begins to go rotten and contaminate water.
For more information about basic care of newts, please see for example Mattison, 1993.
Setup for pair of adult Ribbed Newts.
Preparations for breeding
To get offspring you must have both male and female. In general female salamanders are bigger and sturdier than males. Males in breeding condition have also swollen cloacal region. In addition adult male Ribbed Newt in breeding condition has black nuptial pads on its arms. Its tail compared to body size is also longer and higher than the female’s. On Sword-tailed Newt the tail of the male is the same length as the rest of the body or slightly shorter. Female’s tail is significantly longer than the rest of the body. Some males of this species also have light blue-coloured stripe on the sides of the tail.
Female Ribbed Newt is attaching eggs on water plant at night time.
Properly kept adult animals in good physical condition usually start to breed by themselves. My Ribbed Newts bred all year long, as long as the water depth was kept high, at 20-30 cm. Breeding paused only when water was shallower than 20 cm. My Sword-tailed Newts breed once a year, usually between November and January. There are also many reports of animals staying fertile for the whole year.
Courtship display is a first sign of breeding. Male Ribbed Newt grasps the female from underneath with its arms around the female. When grip is good they swim together around the aquarium. Sword-tailed Newt’s courtship consists of the male pursuing after the female and making specific body and tail movements towards the female. This phase may take several days until the newts get to the final of the courtship display. In the final phase he the male deposits spermatophore on the bottom of the aquarium, and guides the female on top of it so that the female can pick it up to its cloaca. Fertilization takes place inside the female. After some time the female starts to lay eggs on water plant leaves.
Taking care of eggs
After all of the eggs are laid it is recommended to remove them from aquarium. If eggs are left to the aquarium there is a great risk that the adults will eat the eggs in later time. Set up a small aquarium (3 to 10 litres), fill it with water that is taken from adult’s aquarium and place eggs there. It is recommended to transfer all the plants that have eggs to the new aquarium to avoid destroying the eggs. Time needed for development is dependent on the temperature of the water. It is possible to follow development of the embryo through the gelatinous sphere that protects it. Eggs will hatch in 1-3 weeks. If any of the eggs goes bad and starts to grow mould, remove the bad egg immediately.
These Ribbed Newt eggs will hatch quite soon.
Taking care of larvae
When larvae hatch they are about 1 cm long. First couple of days the larvae are quite un-active. They mostly lay on their side at the bottom of the tank. At this first phase of their development they consume rest of their yolk sack. When all of the yolk is consumed, they rise to upright position and start swimming around the aquarium searching for food. This is phase 2 of their development. Salamander larvae are carnivores that consume all kind of very small invertebrates. With small larvae I have got best results using live Artemia salina nymphs, but larvae usually accept dead food items like commercial fish baby foods and even shattered blood worms.
Food must be available at all times. Larvae consume a large amount of small food items and turn them to large amounts of faeces. Some amount of food always remains uneaten, and must be therefore removed from the aquarium. With Ribbed Newt larvae I have been forced to use a daily routine of cleaning debris. Sword-tailed newt larvae are more tolerant to and with them cleaning session every 2-3 days have been adequate.
Just hatched Ribbed Newt larva is 11 mm long. One month old larva is already 29 mm long. It has visible legs and bushy external gills.
When cleaning larvae’s aquariums I use a siphon to suck the debris and about 1/4 - 1/3 of the water out. I always take the replacing water from the adult animals’ aquarium to be sure that water has been standing for a while and that it is the right temperature. There is usually some animal plankton in the adults’ aquarium that the larvae can use as an additional food source. Then I replace the adult’s water with normal tap water.
I prefer not to use aquarium filter on larvae’s aquarium because the larvae can get so easily sucked into the filter. Also the out-coming water from the filter easily creates a strong current that it disturbs the larvae. But if you are able to install the filter so that these problems can be avoided it would possibly help you to keep water in good quality and release you from doing daily cleaning sessions.
As time goes by the larvae keep developing. In phase three front legs appear. They are soon followed by hind legs. After all of the legs have developed larva has reached a total length of 25-40 mm and looks pretty much like an adult animal with external gills. There are many minor differences like flattened head and semi-transparent skin, but animal is easily recognisable as a small newt. Phase four is a growing phase when no major outer changes can be observed by the naked eye. Finally larvae reach metamorphosis. Larva loses its gills and achieves final adult-like form and coloration. My Ribbed Newts achieved at metamorphosis an average total length of 51mm, but according literature they might grow considerably bigger. With Sword-tailed Newts metamorphosis have took place at average total length of 45 mm.
Plastic storage box serves as an aquarium for larvae and small newts.
After metamorphosis many of the young salamandrids raise to land to live “a terrestrial phase” that might take some months or even couple of years. My young Sword-tailed Newts have lived on land at least 5 months before returning to aquatic life. Some individuals have stayed on land even 12 months. It is also possible to avoid the terrestrial phase totally and keep animals semi-aquatic, but I prefer natural way and let them rise to land when ever they want. At terrestrial phase newtlets need a moist terrarium with medium sized water area and lots of hiding places. They require small living (or at least moving) prey objects. I have used vitamin dusted fruit flies (Drosophila sp.) as primary food source. Young salamanders (as well as fruit flies) are able to climb up vertical class, so it is important that younglings’ terrarium has an escape-proof lid.
Ribbed Newts often maintain their aquatic life style also as newtlets. Some of my Ribbed Newt younglings have visited land area shortly, but returned to water after couple of days. Majority of animals have newer risen to land on their own.
Sword-tailed newtlets soon after metamorphosis.
When the young animals have returned to the water, and/or stayed there successfully for couple of months I have declared them as “grown up”, even if their total length is still less than 10 cm. After this “grown up”-point I have kept them like adult animals, sometimes combining them to the same aquarium with their parents. I also think that this it the first possible time to sell the newts to new owners. I don’t want to sell younger animals, because with larvae and newtlets there is always increased possibility of unexpected death. Also many beginners (who most often buy these animals) are not prepared to keep terrestrial salamanders. They tend to stick on the practices intended to full grown aquatic newts, witch leads to numerous of problems with terrestrial newtlets.
Different methods for housing eggs and larvae
Amphibian eggs and small larvae can be raised in different ways. Basic method described above is to remove offspring to their own aquarium. Eggs and small larvae can be raised in a small aquarium that has volume of 3 to 20 litres. The dwelling might be a glass aquarium, or one of those plastic terrariums for small animals that are sold in many pet shops. Also other plastic containers can be used if they are safe for animals. If a container is approved for human food items it is surely save for salamanders. I have also used plastic storage boxes that are often cheaper, and are readily available in large variety of different sizes and forms.
For eggs only “decoration” needed is the aquatic plant that eggs are attached to. When the larvae hatch they enjoy more dense vegetation and hiding places on the bottom. The easiness of cleaning is essential. As hiding places I have mainly used parts of broken flower pots made out of plastic or pottery. They are not the most beautiful elements available, but in practise they are most handy and easy to manage. Besides aquatic plants and hiding places I don’t use any additional decorative elements. I don’t even use gravel at the bottom because it makes bottom cleaning with siphon more difficult. Also no additional heating or lightning is usually needed, and as mentioned before, I prefer not to use filter.
When the larvae grow bigger they require more space. I have kept successfully 20-30 larvae (size about 4 cm each) in storage box that has basal area of 60 x 40 cm. Water depth about 15 cm makes it total of 36 litres of water. If there are too many larvae in a tank they begin to fight and might even eat each others limbs and tails. Missing tails or limbs will usually regenerate, but they are vital sing of overcrowding. If larvae kept together are very different in size the biggest ones might even eat smaller ones.
Terrarium for terrestrial newtlets has plenty of hiding places and only a small water area.
The smaller the aquarium, the harder it is to keep up proper water quality. With eggs and small larvae that doesn’t swim around much other possibility is to build a small pen inside the adults aquarium. The pen might be build out of net, or it can be purchased from aquarium shop (where they are sold for baby fishes). The pen might float freely on the surface, or it might be attached on one side of the tank. The larvae must stay inside and the adults outside, but water and small particles in water (including faeces and animal plankton) should flow freely in and out. When total volume of water is larger, it is easier to keep the water quality up. Drawback is that when larvae grow bigger they need more space that the pen can provide. A big pen doesn’t fit anymore in aquarium, and even a small pen takes some space from limited volume of aquarium.
In some cases it is also possible to raise larvae in same aquarium than adults. With Sword-tailed Newts I have left some eggs in aquarium and they have developed there all by themselves to terrestrial younglings. I know that this can be also done with Cynops orientalis and some other species, but with Ribbed Newts I have never managed this way to raise larvae. The adult Ribbed Newts are too eager to eat their offspring. And even if one of them survives it apparently can’t find enough food to develop.
Cynops larvae are tougher. Recently I have tried not to breed Sword-tailed newts. But because I don’t explicitly destroy all eggs in the aquarium I regularly do find small salamanders that have survived and rose to aquarium’s land area to live their land phase. Apparently they survive with animal plankton in aquarium, because I feed the adults mainly with bigger insects and earthworms. They have blood worms (that would be appropriate sized also for larvae) very seldom. Younglings from adults’ aquarium are no considerable smaller or weaker than ones raised separately.
This “natural method” is very easy. There is nothing keeper must do for the larvae. But naturally amount of surviving larva is quite small. Other drawback is that when larvae are hiding in a big aquarium it is much more difficult to observe their development. At least for me the pleasure from seeing “my babies” growing and developing is one of the major reasons to breed these interesting and amazing animals.
I would like to thank my wife Niina, who has been an enormous help to write this article. She has also been a great help in maintaining our amphibian collection. Without Niina’s support this article would had never been published.
This Sword-tailed Newt larva has fully developed legs. External gills are clearly visible, but the rest of the larva reminds a lot like an adult animal.
Bjornebo, H. 2001: Setup ideas for your caudates. [www.caudata.org/cc/articles/setups.shtml].
Griffits, A., 1996 Newts and Salamanders of Europe. T & A D Poyser Ltd., London. 188 p.
Johnson, T. 2004: Observations of Cynops ensicauda popei habitats in the subtropical rainforests of Yambaru, Okinawa, Japan. Caudata.org Magazine Issue 1, p. 7-25. [www.caudata.org/magazine/caudata_magazine_issue_1.pdf]
Mattison, C. 1993: Keeping and Breeding Amphibians. Blandford, London. 224 p.
© 2015 Joonas Gustafsson