I rang the fish shop two days ago and the guy reassured me that they should be okay in 27 litres.
However, since then, the Gourami's have become very lethargic. They sit at the bottom a lot or float around aimlessley in their little territories. Is that their normal behaviour or is something wrong? I think they are being stressed out by the boisterous guppies.
I've contacted the fish shop and I am awaiting a response. I'm not even bothered about having my money back. I may swap them for some cherry shrimp.
I am so disappointed. I spent all this time and money getting the tank right, and all I've done since I bought the fish is stress out about them. Hardly the positive fish keeping experience I was hoping for.
I'll let you know how things progress..
Thanks everyone, as always...