alexanian, imo tank size doesn't matter for them to spawn as I had a trio in a 2 footer and they laid constantly. (though I never saw the eggs hatch) possible dirty water??? as filter system sucked on it.
Now they are in a standard 4 foot in a malawi condition!!! (i think as I never test water chemistry, just assume it's right by the stuff I add, though since it hatched, i'll test ph and post it here soon).
Btw 2 frys are still doing great. the egg size really hasn't decreased much but their tail end is visibly flattened and kinda looks like a feather.
i'll try get a camera today from a friend so hopefully pictures to come very soon.