Batch of larvae died - why?

[carriw]

Hi everyone
You may remember that a few months ago Tinto laid her first batch and I sent the eggs off to various researchers at universitites, including one studying cognition and learning in cold-blooded animals.

I had some bad news today. All the hatchlings that one university were raising suddenly died overnight. They do not know what went wrong. Does anybody have any suggestions? They have quite a few student projects planned for them (investigating play behaviour, discrimination and learning, rates of growth, effects of environmental enrichment) and so are keen to raise some more. however, they of course want to avoid something like this happening again, so any suggestions you might have are greatly recieved. I have posted some of my correspondence with them below. Thanks in advance.

I'm afraid I have some really sad news. Our axolotls have all died. It happened overnight. They were fine when I left in the evening and when I arrived in the morning they were all dead. We don't know what happened.
We don't think it was the water because all the daphnia (and other food) are fine. Daniel and Charles (an amphibian expert) wondered if they weren't feeding properly but there was lots of food in there. I have put off telling you in case there was one or two left hiding somewhere but I don't think there are. I am really sorry. I really did everything I could to look after them. We are really sad about the little chaps. They were so beautiful.
I don't think there was a problem with heat as it was fine when I left and fine in the morning when I got in. The tank had plenty of plants and an air stone so hopefully the water quality was good. All water was dechlorinated before going in.

 

[Jennewt]

Caudata Culture Articles - Why Larvae Die
The most sensible ideas I have are (1) water quality - if they weren't testing it, then it's an unknown (2) somehow something toxic got in there - hard to say what or how, but in a laboratory setting a lot of things can happen (3) disease - possible that they were suddenly infected, although this wouldn't usually kill 100% of them overnight, there would have been a few deaths during the day or two before the wipeout.

I would ask them what they mean by "lots of food" in there. If they were newly-hatched, too much food can be harmful. Was there any non-live food in there? Also, if they just added the daphnia the day before the deaths, they could have been contaminated with some other organism.

 

[carriw]

Thanks for that link, I will pass the info on and try to find out more. I have been in contact with a person who is raising another load of eggs from the same batch, and he has not had any problems, so I dont think its genetic or maternal (although it was Tinto's first laying).
Thanks for your help.

 

[Jennewt]

There is no maternal or genetic problem that could explain a sudden wipe-out like that.

 

[carriw]

Update - eggs from same batch sent to 3rd person died about 4 days after hatching....I have informed her that this is likely due to not feeding appropriately :-(

Second group are still developing well, no hind limbs yet.

So the group that unexpectedly died recently, we deduce may be either water problems due to too much food / not cleaning old food out quickly enough, or maybe water problems due to something like chloramine (suggested by Ron)? Hopefully some lessons have been learned.

This egg/larvae lark is difficult and sad :-( I am glad I didnt try to raise them myself. I have put a plastic divider inbetween Blanco and Tinto to split the tank in half until I decide what to do about it all.
I get married in 3 weeks so cannot be doing with any more eggs right now! Also don't want my friend looking after them to have to deal with any surprises!
At least the axies should be ok (if a little miffed to be apart and on reduced space) until I get back from honeymoon and decide what is best to do.
I will most likely rehome Tinto and get Blanco a new friend. :-(