How the heck did they survive?

[Ranid]

Earlier this summer my alpine and palmate newts were breeding. I put the two species in 2 small tanks, all the females and like two or three males since I have more males. Then I took out the plants they were breeding on and put them in separate mini-tanks to hatch. Well eventually I got tired of separating them and just combined the two species after taking the adults back out.

I went on a trip and the sitter for my other pets neglected the combined tank, but when I came back there were healthy, larger newt larvae than in the mini-tanks, who later died. Now I feed them, of course, but I'm wondering how they got so large and healthy on seemingly no food? Unless they ate their other tank mates...

 

[John]

You answered your own question.

 

[Jennewt]

There may have been some cannibalism, but I think the larger factor is "micro-fauna". Every healthy well-established aquarium is host to millions of tiny micro-organisms: worms, protozoa, etc. If you look at some of your tank "dirt" under a microscope or a good hand-lens, it's literally swarming with life.

In my experience, larvae consistently do better (grow larger) when they are raised in the adults' tank during the first half of larvahood. During the second half of larvahood, they need larger meals than what they find in the micro-fauna, so they either need to be separated, or fed appropriately sized food within the adults' tank. Of course, the downside is that some larvae undoubtedly get eaten.

By the way Ranid, we ask everyone to register a country in their profile. It helps people writing to know if they should use inches versus centimeters, etc. A lot of questions are much harder to answer if you don't know what country or even continent the person is on.