Ok my funall stock for the 20 long!

[Goldfish loach boy]

Stick to one DG. DGs are cousins to bettas so they have a similar tendency to become very aggressive/territorial around others of the same species, particularly if they are both males (and most stores mainly sell the more colorful males). Also something around 40% weekly PWCs would be better.

Ok, I can do that, one dwarf gourami and 40% water changes, thanks