Doesn't sound like he is OK. Did you treat for ich for 3-5 days after the last symptoms of ich had disappeared? It is not normal for a fish to lay on the bottom 24/7 although some of mine do like to find a niche and hide there for long periods. Does he ever swim around? Come to the top to eat?
Or, she could also be hiding because she has bloat from the feeders, which could also explain why you lost the other fish...
What is your male/female ratio on the zebras?
You need to work on your stock somewhat to lower the stress from that area. I would remove the venustus (it will outgrow the tank anyway) and add more zebras, more yellow labs and a 3rd species. I would also remove the hybrid, since it will most likely try to mate with anything in sight. I wouldn't salvage any fry from the red zebras or yellow labs, though. These two species can crossbreed.
You really need to get some more female zebras...And make sure you have only one male!
You may also experience crossbreeding between the estherae and the Msobo, so I wouldn't salvage any fry at all from the tank unless you witness a spawn, and keep in mind that spawns can take hours, and the fish that begins spawning with the female isn't always the fish that continues to spawn with her.