Losing Larvae

I've lost 2 Salamandra larvae this week (one on Wednesday and one Thursday). Both seemed fine (very plump). I was curious as to whether it is normal to expect some loss or should I be concerned?
Chip

Hi Chip,
some I lose, when they are born, but then normally nearly no larvae die.
Paul

I reckon it's normal especially when they start metamorphosing. Some just seem to drown but if you put them on land they die all the same so I think it's just that they aren't fit enough to make it. Metamorphosis is a very critical fase for them.

Chip, did you lose any since your post on Friday? If it were something contagious, I would expect a lot more would have died. The "usual suspects" in larva deaths are water issues and food issues, but there are other possible causes too. If you lost 2 out of a small number, I would be a bit concerned, especially since they were feeding. Random deaths are usually runts or weaklings, it doesn't usually happen to healthy specimens that are feeding well.

Jen,
This is the most depressing post that I have written. I came home last night and two more were dead (out of around 15 total to begin with). There was a scant amount of debris gathered in one corner of the enclosure - mostly brine shrimp carcasses. I used a cup and scooped them out and replaced this water (app 1/2 to 3/4 of a cup) with water from a well established, heavily planted tropical fish aquarium. Previously I had used dechlorinated tap water for these "mini partials" however since this rearing enclosure was thrown together in haste I thought that it may be better to use cycled water. Since the volume of the replacement water in no way came close to the total volume in the container I did not think that temperature shock would be an issue. This morning all remaining larvae were dead. Needless to say I am really discouraged. Even though I consider myself still a novice with caudates I would like to think that otherwise I'm a somewhat experienced herpetoculturist. Other than water quality the only other factor that I can wonder about is the use of blackworms. I did not have any deaths until I started using them (although I have also fed them to my fish with no apparent problems). In any case I appreciate all of the advice that you and the others have given me on this issue. I plan on setting up a permanent aquarium with plants and pond water so when I hopefully have the chance to work with larvae again I will be better prepared.
Chip

One of the other possibilities in early stage larva death is nutritional insufficiencies that have been passed down from the female. For example, if there is insufficient maternal levels of vitamin A or carotenoids during ovulation then there may be an increased mortality to developmental issues and/or immunosuppression.
I doubt that it was the blackworms as pathnogenic and toxicity issues would have affected the fish as well as the salamander larva. The only way this would have occured would have been if the worms decreased the available levels of oxygen (by decomposing and/or respiration) or increased the levels of ammonia and/or nitrite (which would occur with the brine shrimp). Even using cycled water these levels can spike fairly quickly if there is sufficient bioload in the volume of water.

Some thoughts,

Ed

<blockquote><hr size=0><!-quote-!><font size=1>Francesco Spallone wrote on Saturday, 04 February, 2006 - 10:39 :</font>

"I reckon it's normal especially when they start metamorphosing. Some just seem to drown but if you put them on land they die all the same so I think it's just that they aren't fit enough to make it. Metamorphosis is a very critical fase for them."<!-/quote-!><hr size=0></blockquote>
Hm ..., Francesco - in all the years I bred S.s.t. I lost max. 1 % in metamorphosis and also lost very few larvae.
When problems develope I would set all larvae separately in small (0,5l) boxes and change the water each day.
Paul

Well perhaps I wasn't clear enough: out of a group of 30-40 larvae it has often happened to me to lose a couple in the way I mentioned before and more frequently in gigliolii rather than salamandra which is more similar to terrestris.
However this is clearly not the case since in the end 100% of the larvae died
Francesco

Like Ed said. Their is a good chance they were weak when born. If I remember correctly the parents are wild caught. The wild caught animals could have been stressed enough in shipping and handling to cause this.

Chip, I'm very sorry to hear it. Having a cycled tank is optimal. The best alternative to that, in my opinion, is small containers and doing a 100% water change + wiping out the inside of the container every day or two. In other words, cycled or semi-sterile are the two methods I use.

There are various reasons it could have happened, as mentioned in the posts here already. All I can suggest is try again, and try various methods until you find what works. Better luck next time.

(Message edited by jennewt on February 05, 2006)

I appreciate the comments. I suppose that it makes me feel a little better to think that it may have been due more to shipping stress and possibly less to my husbandry methods (Ed- I forgot to mention that I did have an airstone in the container). In any case I still hate the loss of the animals but I will be better prepared next time.
Chip

I tend to not clean the inside of the containers unless there is a death or deaths as this removes the biofilm that cycles the tank.

Chip if you are caught short again like this, acidify the water slightly to switch the ammonia to ammonium (non-toxic) and add a little aquarium salt as this reduces the toxicity of the nitrite.

Ed

Salamandara larvae usually live in small, clean and cold brooks.
My practice in rearing them is - clean water and clean water and ....!
So I had the best results when using small boxes (10*10 cm) - one for each larvae, and changing the water each two days. I only use tap water (standing one day). Temperature should be clearly under 20 °C, better max. 18°C.
Paul

sorry to hear about the larvae chip. i bred my terrestris for the first time last year, and out of 27 larvae, 10 died about 3 days after birth(all on the same day). but following this incident the rest of them sucessfully morphed. even though i'm relatively inexperienced with caudates (and may well have done something wrong) i can't help thinking that something must have been physically wrong with the ones that died, because they were feeding the day they died, and i did nothing different with the remaining larvae. i was warned about losing a few on metamorphosis through drowning, but they had no problems at all

I agree with Paul; I think the problem should be found in water quality. When there are dead shrimp...the water is too dirty! In my experience dead larvae get either born that way (together with unfertilized eggs) but after that you hardly losse any. I only had one time an infection in which all the larvae had small lumps, but they metamorphosed with them After that the died one by one.

An additional thought: dead prey items can extremely quickly result in high ammonia levels, especially in aquaria with very little substrate for bacteria of the nitrogen cycle. Besides direct toxicity for the larvae, ammonia affects the skin and gills of your larvae, making them more vulnerable to, otherwise non-pathogenic bacteria. The problem is that, when one larva dies due to a septicemia, huge numbers of these bacteria will be present and the chance that other larvae will be affected increases greatly. I used to raise larvae using the same "clean" system: small containers without substrate and frequent water changes. However, I am convinced that using a more stable environment (larger volume of water, a large surface substrate) is highly beneficial. Therefore, nowadays I use large containers (approx 20 l) with a 5 cm substrate of coarse river sand and losses of larvae are really minimal.
Another thought: I know that it is written in all terrarium and aquarium literature that one should use "aged water", eg from tropical fish aquaria. There are some major drawbacks eg infections (notably very highly prevaling Mycobacterium and protozoan infections). I always use regular tap water that has been aerated for 48 h and this works really quite well.

Hi Frank!
<blockquote><hr size=0><!-quote-!><font size=1>Frank Pasmans wrote on Wednesday, 15 February, 2006 - 11:19 :</font>

"Therefore, nowadays I use large containers (approx 20 l) with a 5 cm substrate of coarse river sand and losses of larvae are really minimal. "<!-/quote-!><hr size=0></blockquote>
Nearly the same observation!
With small, clean boxes I have nearly no losses - but much work. So if possible I keep them in my garden in a tank 80 * 35 * 40 cm with plants and rocks with a lot of holes but no substrat. I prepare the tank months before the larvae come in. Then Daphnia pulex live in it when I need the tank for the larvae. Very good results but little work.
Paul

Yes, exactly. I have found 2 methods that work well: (1) an aged cycled tank with plants and pebbles, or (2) clean containers with total water changes and fresh containers frequently. The first needs less maintenance, but is not always available.

I found problems occur more often if one is trying to "steer a middle course" between these two methods - keeping larvae in a new tank with only partial water changes.

I am preparing an article about "Why larvae die". Would anyone be willing to contribute any "case histories" (specific examples of larval death from known - or suspected - causes)?

When I rear larva, it really does work better for me to do 100% water changes but I leave the biofilm alone unless there have been deaths. This typically results in a algae growth on the sides of the container (see the picture under the Cynops cyanurus post for what the tanks end up looking like) which seems to reduce mortality for me.

Ed

ed, do you use tap water, and if so how long do you "age" it for before use. i try to use rainwater collected in a barrel, but even here in rainy manchester its not always a reliable source