Illness/Sickness: Swollen C.pyrrhogaster larvae

[evut]

4 of my Cynops pyrrhogaster larvae became very swollen overnight. They all come from the same tub (separated them from the other 4 now which still look normal). All other tubs are ok.
I change half their water daily and put them into clean tub every other or third day. Food is mainly artemia.

What is wrong with these larvae please? I can't think of anything that would be different in their tub, I clean and feed all of them at the same time and the same way. They are bloated mainly around the chest area.
Thanks for helping me.

 

[evut]

I was very pleased to see that there are no more bloated larvae this morning and the ones that were puffy yesterday look a lot better today. Two are back to normal, one is just slightly swollen and only one is really big but better than yesterday.

I would still like to know what could possibly have caused this. Any ideas?

 

[Azhael]

I´m glad they are ok, Eva.
I honestly don´t know what to tell you...it looks like "classic" larva bloat, but the causes are unclear. One thing i know is that it only happened to me in the past when i tried raising larvae in shallow, small containers with daily water changes. Since i changed to more stable rearing conditions i haven´t had such a case.

 

[evut]

Today all the larvae are looking normal. I am extremely happy as these are some of my more advanced ones and seemed to be doing really well until now.