There is no way you can keep any cichlid in a 20L setup. Literally the only thing that could go in there are maybe like 5 guppies or a betta. Badis is too big. Crawfish is WAAAY too big, as is the pleco. You could maybe have a snail in there.
For all the imperial system people, 20L is 5.28344 gallons.
Yeah sorry for the confusion for imperial folks...20L is 20 gallon long tank. Not 20 liters.