White Cold Water Mountain fish not eating

Question
Hi,
We have just set up a new 14 litre tank. As advised at the shop we left it running for a week before adding fish and then 5 days ago added 2 white cold water mountain fish as we were told these are very good starter fish. However, they don't seem to eat at all. We have tried pellets and flake food but seem to be taking it off of the surface after 5 minutes because the fish don't eat it. They seem happy enough and are active, they just seem to ignore the food completely.
We have a filter on the back and have been told to only change the water (10%) weekly. Also how many fish would you add to a tank this size, i keep seeing conflicting figures between 2 and 4 litres per fish. Would plattys or guppys be compatible. Thank you for your time.
Kevin

Answer
Hello Kevin!

Ok, I'll go slowly, one question at a time.

They won't eat because they are not in schools. They may eventually take food, but it won't be at first. They are schooling fish and need to be in groups of at least 6 to be happy.

Water changes should be a minimum of 50% weekly or preferably 25% twice a week.

I would actually not put any fish in that tank size. It is just too small for any fish to be happy, other than a single betta or maybe a trio of guppies. But even then they wouldn't live a full lifespan.
That 2 and 4 litres thing, is just another on of those rules that the pet stores make up. There is not set rule for stocking, and that is one of the worst one's I've seen. Do not listen to any of those rules, they are just made up so the pet store employees have something to tell the beginners.

Both would by incompatible because platies and guppies are tropical fish, and your other fish are coldwater.

-Nick