16 dead babies :-(

I have had 16 larvae die in the last 12 hours, and I'm not sure why. There's no obvious defomities, no fungus, no injuries.

I had them in small tubs:
1L tub with 1-week-old larvae - 10 dead, 5 left
1L tub with 2-week-old larvae - 4 dead, 6 left
5L tub with 2-week-old larvae - 2 dead, 25 left
All tubs have fresh water every day, they have some pondweed for hiding and O2 production.

They were all doing fine until last night. Having sought advice here because I was having trouble hatching brineshrimp I was told to increase my salt concentration - which I did. I fed the BBS to my larvae last night after a good rinse as usual, and this morning I have 16 dead and another 3 that probably won't make it. I was using decapsulated eggs so shells are not an issue.

Could it be the salt that killed them? Could the BBS contain too much salt? I rinsed the BBS under running water as always, I changed the water after 4 hours as always to get rid of dead BBS and waste, nothing else has changed. I expect the odd casualty, but not that many on one go.

Any help would be appreciated. I am really upset at losing 1/4 of my babies

Did you use dechlorinated tap water for the water change? The last time I had anything like this happen (it was angel fish fry not amphibian larvae though) it turned out the water company had added extra chemicals to the mains water supply during maintenance. If you contact them and explain the situation they will notify you in advance next time.
It's just a thought but it would explain why different containers had the same problem on the same day?

Dechlorinated as usual. Although I didn't test the water it's the same tub of water I used for 2 days previously.

Thats the thing that got me - the fact that all 3 tubs were affected at the same time. If it was one tub you could argue infection, but all 3 togeather is odd.
With the distribution of fatalities as evidence whatever it was had less of an effect in the larger tub, and therefore it must be more dilute. The smallest fry in the small tub were worst affected therefore the concentration must have been greater.

Conclusion is that it was a contaminant of some kind, but would salt have given this result? Since Holtfreter's solution contains over 3g of salt per litre I am now wondering if it was something else, since the maximum salt I could have intorduced would have been fractions of a gram with the brineshrimp.

I think if the replacement water had been standing around for 2 days it should be safe, I got caught out by using it straight from the tap with dechlorinator added. I honestly don't know about the salt as I don't feed brine shrimp very often, although plenty of people do without any problems at all. Do the tubs have anything else in common other than the water and the brine shrimp? It seems very strange to have the same problem in different tubs all on the same day.

I can't think of anything else.

They are in the same room, same water, same food, same as the previous 2 weeks. The only thing that changed was the concentration of the salt solution used to hatch the BBS.

What's your tub cleaning regimen like? If you're not wiping off biofilm between cleanings, it can build up and foul water quality fast enough to kill small larvae.

HI Jo,
sad news indeed. I have to say that your otter 10 babies are all doing well so far.
When did you first notice any issues?
If everything else has been the same, I guess it is logical to thing it was the salts concentration...maybe the levels were tolerable to begin with the but accumulation for 3 days has made the difference.
The other thing you might want to thing of, even though they are in the water, is potential gases contamination of some sort. I had outbreaks like that and is always very sad and frustrating, and you are doing the right thing trying to find out.

OK, cleaning regimen: Each group gets put into a clean tub with fresh dechlorinated water every day. I do this about 4 hours after feeding as the BBS are generally dead after this. I use a coarse net to catch the babies and not get any dead BBS in the new clean tub. They have some pondweed in with them for cover and O2. I use the turkey baster if I see little orange poops in the tubs.
The old tubs are cleaned with hot tapwater and a paper towel and then left to dry ready for the next day. I don't use chemicals, soap, vinegar or anything other than hot water and elbow grease.

They have all been absolutely fine until I fed them yesterday with the BBS hatched in a stronger salt solution. They have been in my living room the whole time, next to their parents' tank, so I doubt environmental contamination is an issue - either me & hubby would have noticed or the other axies would.
I am now down to 24 larvae from 56 , but they all seem to be OK. I have given them daphnia today, grading them so the smallest babies get the smallest daphnia, and I rinsed my BBS grading filter with hot water before I did this just in case.

@Danicc - I am very pleased to hear your little bunch are doing fine .

It is not the salt measurement, as long as you are rinsing. My previous problems with death in hatchings, is starvation. The hatchlings need food, in front of them all the time. If you have light in the room, the bbs will follow the light. Usually in a upper corner of the tub. I have been working on and trying out a shelving system that has slits on the bottom of the shelve and lights below the shelf. The bbs will stay on the bottom of container....hence, food in front of their face all the time!! (this is the key) Now, since the last time that I talked to you, about the salt measurements, I tried something new. I have 4 jugs (hatcheries) going. I tried 2 with sea salt and 2 with regular (non-iodized) salt. Sea salt produces 98% better. The second thing I tried was 2 of the bottles with the full measurement of salt and the other 23 with half the measurement. If you remember in the last post, he told me to fine tune to get optimal hatch rates. I saw little difference so far. ---Not done tuning.... You do know the color difference of alive bbs and dead bbs? Just asking.....temp of water, light,....in hatchery? Now, I rinse the bbs and then put them in Holtsfeter solution, that way they live until the next batch. This way I can CONSTANTLY have food in front of the juvies face. Get the food (and lots of it) in front of juvies face...........this is the key to success!! Also, what is the salt concentration of the juvies holding trays. Are you having a bbs die off, and polluting the water? I ask these questions, not to insult, because I know that you know what you are doing, I ask because I want you to get your focus off the salt concentrations used in the hatching of bbs. GET THE FOOD IN FRONT OF THEM!!!!! They don't have the strength to chase food continually. Not way to store fat for energy.
Again...CONSTANT SUPPLY (alive) food, light below them so that the (alive) food stays on the bottom and is in front of them.
Trace

Oh......and keep the water level very low in the juvies tray. This also helps concentrate the live food in front of the kids faces. .....Light below and low water level.... My success is now 98.7% :happy:

Salt alone is not the problem unless you have gone very high. I used to attract surplus brine shrimp and pipette them into 1% salt solution and keep them in shallow dishes in the fridge. I pipetted them on without further rinsing. Axolotls do not seem to be stressed up to about 7g/litre salt and adults have experimentally tolerated 10g/l (sorry I haven't the reference handy from memory at this level there are blood chemistry changes involving retention of urea in the blood stream).

I don't know why but people never seem to measure ammonia when raising larvae. Crack out the ammonia test and pH and see what the levels are before that water change every now and again. I was horrified at the level in one of my batches, you may just need bigger containers or even more frequent changes.

OK, so the salt is probably not the culprit. But starvation isn't either - most of the dead larvae had full orange tummies from BBS - I was feeding them plenty, then clearing out the dead BBS after 4 hours. The first ones died before I had cleaned the tubs, I thougt nothing of a couple of casualties. The water was kept 1" deep, but I din't bother with quality check as I was changing 100% daily. I can't measure salt levels as I don't have a salinity meter.

I will check the ammonia levels. And I'm going to split the reamining larvae into smaller groups.

I have decided to move them on to daphnia anyway, so dead food contaminating the water shouldn't be an issue, and neither should salt.

Should have no dead bbs.... a.m. and p.m. water change(s). I think you just answered your question. :uhoh:

willowcat said:

Should have no dead bbs.... a.m. and p.m. water change(s). I think you just answered your question. :uhoh:

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And I change the water 4 hours after feeding - at that point there are some dead BBS and some still moving. No dead BBS lying about to foul the water. I do have some idea of what I'm doing, so please stop with the <rolleyes> attitude.

Just tested the water - Ammonia not registering after a water change at 10am - so I don't think thats the problem either.

I know that you know what you are doing. I indicated this in a couple of post ago. I am trying to keep you cheery. Okay, now...are you using sea salt? Are able to keep bbs on bottom? Are the containers in a well lit room?

I use sea salt - both for BBS and salt baths. I have my larvae in tubs about 1-2" deep inside an old tray, the lighting is ambient daylight from a window about 4ft away, and the artificial light is not bright. The BBS are completely accessible, I have had nor problems until Saturday.

I have given up on BBS for now, the larvae are nearly and inch long, and I have daphnia and will use those.

Hi sorry is this your first time raising hatchlings in plastic tubes?

I have a friend who swears against using plastic tubes for raising them because she believes the plastic releases toxins which kills off the babies - this was after she lost an entire clutch when using plastic tubes and hasn't had any problems since switching to normal glass tanks (she has had numerous very successful years of babies now).

Just a thought to consider. I know it would be hard to believe since you do daily water changes of 100% but so did she and its the only thing she can put it down to

Possum63 said:

Hi sorry is this your first time raising hatchlings in plastic tubes?

I have a friend who swears against using plastic tubes for raising them because she believes the plastic releases toxins which kills off the babies - this was after she lost an entire clutch when using plastic tubes and hasn't had any problems since switching to normal glass tanks (she has had numerous very successful years of babies now).

Just a thought to consider. I know it would be hard to believe since you do daily water changes of 100% but so did she and its the only thing she can put it down to

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I can see your point, but why would half die and half survive? And why would they be fine now? I haven't got any glass tubs or tanks to transfer them to, so it's kinda moot anyway.

But I'll keep it in mind for the next clutch - thanks for the input.

There could also be genetic issues at hand. Some lethal genes will allow a larva to survive for a few days/weeks, only to die suddenly.