I am seeing conflicting advice on numbers to keep them in.
I have a 30 L tank with a nice big surface area, cycling at the moment.

Some say pairs, others say trio 1M/2F

Which is it? And if the trio do I really have enough room?

Thanks.

1 Male per 2 Female

Not Strictly true, i have 2M and they get on fine, it depends on the fish's personality mainly, i was jsut lucky to get to nice males,

I agree with Dan. I have 2M's and they, mostly, get on fine - barring a couple of instances...

With gouramis, it is more about space/territory and a little bit of character. Dwarfs are quite agressive, and 30 litre is smallish for a trio. I would simply keep 1 male dwarf in that size tank as a centrepiece, and combine it with a nice shoal of small fish, such as tetras or rasboras.

Actually yeah... going by the 1 inch for every gallon of a tank ruling, 30L converts to about 6.6 gallons. Really, your tank is way too small for any ammount of Gourami. The Rainbow, Powder Blue, Red or Neon Blue Gourami's need at least a 15 gallon tank; and even the Honey Dwarf needs a minimum of 10.

I'd seriosuly advise you against having a Gourami in a tank less than 10 gallons. You'll only end up with a very unhappy and stressed fish. If I were you, i'd get a school of White Cloud Minnows - they're small, very playful and interesting little Danio fish. A school of about 4-6 would most likely be happy in your tank... but even that may be a little of a push.

it is 10 US gallons, and 6.6 imperial? gallons. The inch/gallon rule is normally applied to US gallons, so 1 dwarf should be fine.

If the fish have goods personalitys then they will be fine, it also depends on the maturity of the fish, young fish tend not to fight as they are not mature.