Greater Sirens

Quick Reference Care Guide

Housing:

• Up to 100+ gallons depending on size

• Water MUST be dechlorinated and should be properly cycled

• Water should be kept between 60F and 75F ideally. Room temperature is typically fine as long as your house stays under 80F

• Sand substrate (best option) or bare bottom tank. ABSOLUTELY NO GRAVEL

• Tankmates should only include other, similarly sized greater sirens and tiny fish and invertebrates intended to be eaten. DO NOT MIX SPECIES, NOT EVEN OTHER SIREN SPECIES. DO NOT MIX WITH TROPICAL FISH BESIDES TINY FEEDERS

• Your tank should have a secure lid. Sirens are escape artists, and are extremely strong. Escape attempts are especially frequent when they are introduced into a new tank.

• Sponge filters are the best option, but mechanical filters are ok as long as there is 100% absolutely no way for the siren to get into the intake.

• Plants such as Anacharis, Vallisneria, Java Moss, and Water Lotus are excellent choices, as sirens really enjoy both hiding and having things to tangle up in.

• Hides can be easily made from PVC or ABS pipes from your local hardware store. Pavers and landscaping stones can be stacked into caves.

• normal aquarium lights are fine so long as the sirens have adequate hides and cover.

Food and Diet:

• Particularly young animals will prefer live and frozen food, like blackworms, bloodworms, and brine shrimp

• Most Greater Sirens will eat all kinds of food. Earthworms are a particularly nutritious favorite. They also love to eat snails. Frozen fish food is gladly accepted as well as sinking carnivore pellets. They will opportunistically predate on small feeders like endlers guppies and ghost shrimp, but largely prefer to scavenge off the bottom for some easy scraps. Greater Sirens are one of the only salamanders known to eat plants on occasion as well.

Lifespan:

• You’re in it for the long haul. We honestly don’t yet know the limit of these animals’ lifespan. Think 20+ years if you do a good job.

• These guys get big. My breeding pair were about 30 inches and as thick as my wrist. They’ve been recorded at over 3 feet long, and supposedly been sighted at 4 feet long.

Project Status:

Captive breeding successfully accomplished as of December 2019! No recurrences, awaiting F1 generation to mature.

Animal Availability:

None Available, will likely be years until the F1 generation is ready to reproduce. Breeding may occur again sooner if I acquire another adult female.

Breeding and Reproduction information

For the sake of context, understand that as far I know, at the time that I publish this, I am the only hobbyist who has successfully bred this species in captivity and documented how it was done. Everything I write here should be seen not as a definitive guide, but as a starting point for reproducing my success for yourself.

Due to the severe lack of available knowledge regarding S. lacertina’s life and breeding habits, the only information I had to go off of was what shamefully little I'm sure you’ve already found through google, and a single scholarly article that briefly described nesting and mating in S. intermedia (lesser sirens). Everything else that I know is from personal observation of these animals as my personal pets over the last ~8 years. I will try and highlight the most pertinent details, but I encourage you to read through to the end.

The enclosure that I setup was a 250 gallon (946 L)  glass aquarium that I purchased second-hand, and set up outside on my back patio, however I believe it could also likely be accomplished in a rubber or galvanized stock tank, or an in-ground pond of sufficient size. It may be possible to accomplish this in a large indoor tank as well, if the room gets a large amount of natural lighting from a window. My Female siren was about 30” (76 cm) at this point, and my male was about 26” (66 cm) both were as thick around as my wrist - to give you an idea as to why they need so much space.

For circulation and filtration, I used an appropriately rated pond pump, contained in a debris-blocking mesh bag attached to a pressurized filter canister (the ones you can get from the pond section of any major hardware store garden area). I also opted to have a heater (rated for much smaller tanks) on each side of the tank, set to 50F (10C), just to ensure that on particularly cold nights, freezing temperatures would not affect the tank too harshly. Fortunately, sirens seem to be incredibly tolerant to different ranges of temperature, so long as there has been seasonal acclimation. The coldest days of winter get just below freezing where I live, and the hottest days of summer/fall are over 115F (46C). The water at some times would get past 80F (27C), which would be fatal for a large number of salamander species. I spoke at one time to a keeper in the UK, who said their pond would form ice on top, and their siren would be just fine in the freezing water; so they really can tolerate a huge variety of water temperatures. That being said, this is all with typical, gradual seasonal changes. Sudden, unusual and extreme changes in temperature, both hot and cold, can still be very stressful and fatal, even within those ranges.

For substrate, I used a very large amount of sand. “Play sand” is typically just fine to use, but requires a heavy amount of rinsing to remove excess dust and sediment from the water. Pool filter sand is about the same, but with considerably less rinsing needed. For this tank, I used a full 4-6 inches (10-15cm) of sand across the entire bottom to try and replicate all the sediment and silt that would normally be at the bottom of a natural pond.

The rest of the tank consisted of 2 pieces of wood, weighed down by large flat pieces of slate pavers, and lots of plants. When I was reading that single article on S.intermedia, it stuck out to me that they frequently nested in water hyacinth fields in their native regions. Water hyacinth (Pontederia crassipes) is a free floating plant that has long roots that drape down vertically. I had also observed that in many places that support water hyacinth, you will also find water lilies (Nymphaeaceae sp.) and water lettuce (Pistia stratiotes). With this information, I fully stocked the tank with all 3. Something to note, is that if you are trying to do this indoors, you may need specialized grow lights, as all of these plants need more / fuller spectrum lighting to survive than typical aquarium LEDs or house light bulbs. 

What I now know, is that water hyacinth specifically, offers a perfect nesting site for many reasons. The plant itself is fairly big and bulky, grows very close together, and is coupled by a thick, matted, fibrous root system just beneath the surface that can extend 2 feet down. It provides an excellent visual and physical barrier from predators at the top of the water in continuous areas of several square meters or more. These root systems also collect algae, peat, and other detritus to form matted balls of fibrous plant matter that eventually collect on the substrate below. This plant matter ultimately serves as the nesting medium for the sirens. I believe that they need such a closely matted material so that they can easily keep together the 1000+ eggs that they can lay in each clutch (mine laid just over 1200). This would make it easier for the male who then wraps his body around the nest and fans it with his tail for the next month or 2 while simultaneously viciously defending the nest from any and all intruders including the mother and my hands.

Once you have the tank setup, all you can do is wait. My pair were housed together for a year indoors prior to being moved to my backyard. They were in the outdoor tank for about 6 months (summer to winter) When i noticed the eggs on January 9th, 2020. Unfortunately, I did not observe any courtship behavior leading up to the event, as the tank was entirely overgrown at this point. They were likely laid recently, as the eggs had not shown any signs of development yet. As soon as the eggs were showing signs of viability, I removed the entire nest. While doing this, I was bitten 2 or 3 times by the male with an aggression I had never witnessed before. My hand and arm were too large for him to get a good grip on with his mouth, so it was more surprising than anything else, however, this cued me to check in on the female. After searching through the forest of algae and water hyacinth, I managed to pull her out, and she had several large bite marks on her where there were relatively shallow, but open wounds accompanied by about 5 other bite-shaped markings on her skin. I mention this specifically because multiple complications from the wound ultimately led to the female sirens’ death, and this was with competent veterinary intervention as well. It is of the utmost importance to monitor all of your sirens during breeding season. You may need to separate certain individuals for their own well being. It is not certain, but likely that biting is involved in courtship before-hand in addition to occurring while guarding the nest.

The nest itself was 2 large matted clumps of plant matter with a large number of firm, rubber-like eggs (as opposed to the soft gelatinous eggs of many other species) enmeshed with the detritus. They started off entirely white and opaque. Over the next 3-6 weeks, the eggs slowly started developing and began to become more transparent and soft before hatching. After removing the nest, I placed it in a 5 gallon bucket full of water from the parents’ tank, and put a somewhat powerful airstone beneath the nest to provide aeration. I am unsure to what degree the aeration of the eggs helps, but given that the father will continuously fan the nest with his tail, I imagine it plays an important role in imitating that movement regardless of my exact understanding of the mechanic. About 90% of the 1200+ eggs were viable, and roughly 99% of the viable eggs developed to hatch normally. Interestingly, the hatchlings are born with very slightly developed arm nubs and bear a unique pattern on the top of their head that is distinct from that of S. intermedia. I also had a single hatchling born with a second partial head attached to the side of its main one. Unfortunately, it only lived several weeks.

To feed the young, the only thing I had prepared was several brine shrimp cultures, and they were not reliable cultures. This unfortunately led to me only being able to successfully raise approximately 150 of the babies to stable juvenile size. What I have since learned is that siren larvae thrive much better in a naturalistic setup as opposed to a sterile controlled one. A much better way to raise the hatchlings is to use a large plastic storage container with 2 inches of sand, plenty of java moss and anacharis, an aerator, and some detritus / a bit of silt from a local stream to seed some nearly microscopic food options. Set this up right when the eggs are first laid, and by the time they hatch, you will have a healthy supply of natural food for them that will last until they are big enough to eat more commonly available foods like daphnia and blackworms.

Sirens of similar size typically do very well being housed together, and the young do not tend to cannibalize - but they can be very enthusiastic eaters and can bite nearby arms and gills in the excitement. Adult sirens will eat the hatchlings after the eggs have hatched, and if the size difference is great enough, it's very possible larger juveniles are cannibalized as well (although i haven't observed this personally)