Fry questions

Here's a bunch of questions about my severum fry. The first few days
after hatching, they kind of lay on the bottom under parental protection
until free swimmers. I don't see any yolk sacs, so exactly what are they
living off of all this time?

The last batch I removed from the parents 2 days after they were free
swimming, to a 20 gallon tank of their own. I reduced the filter to a
dribble, and put a fine mesh over the intake hose end. I fed them Liqui-fry
a few times a day. A hundred were reduced to 25 after 2 days... then 10
after 5 days, now 4 decent ones left after 3 weeks. Is this a normal
mortality rate, or did I remove them way too early?

This 20 gallon was empty for a few months, and used to have fish and
snails off and on, with the filter going all the time. I haven't seen one
snail in months. Now that the babies and food are reintroduced, the snails
have reappeared out of nowhere! Were the eggs laying dormant?

--
JK Sinrod
Sinrod Stained Glass Studios
www.sinrodstudios.com
Coney Island Memories
www.sinrodstudios.com/coneymemories