Firstly, get them out of the sun.

Because you don't know what they are ,
Try a variety of foods.
You dont have to see them feed by the way.

Good food souces are algues, you can get tablets of spirulina and grind it.
Live food like waterflees (not sure how you call those )
Some leaves and sediment would be ok to.

We usually use leaves of the beuk and eik and the little pineapple like fruits of the els,
Also not sure how this is called by you guys

I'll try a translation tool to change the dutch names to English


the time it takes them to metamorphose can't be told.
it can differ for different species and also depends on food available and temperature of the water.