Question: Density and Feeding question regarding Spotted Salamanders (and in general)

I am a beginner to amphibian raising, especially with respect to salamanders and newts. Unfortunately, I have had issues with a couple larvae cultures slowing dying off (A. texanum and A. barbouri) after about a month (I am guessing due to the yolk supply running out by then).

We use a Daphnia/Invertebrate mix from Carolina Bio supply, but I must not have been giving enough. Initially, I was feeding every three days (following what I was told by my boss) but after these failures, I don't want to fail again with the spotted salamanders we need to raise. Long story short, I am curious if anyone has had experience raising in the lab and could give a beginner a better procedure or guidelines to feeding strategies for these guys?

Right now we have two kiddie pools outside with some green water and now an excess of Daphnia that have about 100 - 200 larvae, which seem to be no longer dying (well, in that last two days). We also have ~12L plastic tubs inside with about 20-40 individuals. Are these densities okay, or should I try and individually separate them (we do have 2L and 1L containers, as well)?

Would there be any need to supplement the diet with something smaller?

Also, can water changes stress out a morbid larvae enough to cause death?

Any advice is greatly appreciated.

That sounds awfully dense.

I would raise them 2-3 per sandwich-size container, and always keep them stocked with fresh daphnia. In a 2l tank you can probably keep 4-5, until they get bigger. Keep in mind these guys are pretty cannibalistic.

Your others probably starved to death. Their yolk is absorbed within 24-48 hours after hatching, and since you were only offering food every couple of days, they weren't getting the nutrition they needed.

You can raise these guys much the same way people raise little axolotls. I used sandwich containers and daphnia, with about 50% water changes from my adult tank every day. Since you don't have an adult tank from which to pull water, you should have buckets with standing, aged water.

Thanks for the response, I am starting the process of pairing them up in 2L containers with space permitting and maybe up to 3 or 4 if I start to run out of space. They seem to be eating better and none have died so I think they are doing good now. Thanks again