Hi Patrick,
sad to hear. I had also a bit of a unlucky hand with the fry.
It´s hard to say for me what can be the reason but I can tell my
observations.
Like I wrote before, with my first fry I had a high loss rate in the first days
till I changed the setup of the box. They were doing fine till an age of 4 weeks
than I noticed that every day one or two were swimming weard. They were swimming
with the head down and it looked like the tail was drifting up, in the end of the
day they were hanging at the watersurface and they were turning slowly white from behind.
So checked one of them with a loupe and there were little white dots moving around on this
little fish. This little creatures were eating somehow the little fish alive.
I took all the fry left and put them into a breeding box from Se.. which I hung into
the tank of the parents. The sponge filter in the tank was placed in a way that the water
is dripping all the time into the box. It works the same way like the “Gerdkasten”.
They are all healthy and grew a lot.
The second load of fry I seperated grew well without any losses the first 1,5 weeks.
Unexpected I had to go somewhere for 5 days and had to show my girlfriend how to feed
artemia. When I came back all of them were gone. 🙁
My fry could take artemia from the first day but I noticed a development in eating.
First days the artemia have to swim more or less into the mouth of the fry and you have to feed a lot. They are not very active hunters, that´s the time where a lot of artemia end up dead in the breeding box. So cleaning the box is a fulltime job.
After some days they are hunting actively and swim to the food.
I think like Peter, it´s better to feed livefood that stays alive in sweetwater till the fry is hunting actively.
Another risk was for me that the fry is hanging the first days in the drifting plants, when they are a bit older and hunt food they are moving mainly on the ground. That´s where I guess they are very sensitive to bacterias if the box is not 100% clean.
All in all, keeping the little plastic box totally clean is very hard and time consuming.
I think I will try the “Gerdkasten” or already running tank in future.
Also interesting for me was to see that the Betta brownorum, I was raising up in the same boxes
and the same age, where doing fine. I didn´t lose a single fish.
Volker