For bullies I would say you could keep 3 or 4 adults (1:2 or 1:3 or 2:2 m:f) in a 2x1x1 ft tank, you might be able to get away with 3 males with well placed caves rocks but it would be better to keep the male population lower so the dont bicker too much.
for any of the galaxiids I would say a 3ft length is the minimum. I have an inanga that is very deformed after swimming into the end of the 4 ft tank at high speed. any of the large galaxiids I would say 4ft would be the mim (banded kokopu, giant kokopu [even these will outgrow a 4 tf], koaro, shortjaw kokopu [i wouldn't recommend keeping shortjaw as they are much harder to keep and there are they are in serious decline])