The fry are tiny & slow growing. I have one here that is about 8/9mm at
a
month old so they are easy prey once they get out of their cave.
They are also quite tricky to feed.

My Zebras are now in a tank wich they only share with a baby ancistrus,
for
keeping algae at bay. I have 8 in a 120 liter, and are a bit worried about
that not being enough for establishing a good balance in the tank,
bacteria
wise.

Have you published any information about how you went about getting them
to
spawn? It would be very interesting to read

Mike Edwardes is the guy you want;-
http://mike-edwardes.members.beeb.net/Hzebra.html
I bought his colony when he changed to amphibians.Mike reckons the fry do
better removed as soon as they leave the cave.

They do better in planted tanks but bare bottoms with java moss & fern on
rocks or wood make for easier maintainence. The more small hidey holes the
better & they do seem to like terracotta.
Not having dither fish means you can keep Daphnia in the tank for a food
source.
The tiny fry need frequent feeds of tiny live/frozen foods.

HTH
Sue