Help! Tiger Barbs and Gourami acting strange?

I recently purchased the top fin 10 gallon kit. I had my water cycling for a week or so and I have a Opaline Gourami and 3 Tiger barbs. I had the Gourami first, and just added the Tiger barbs yesterday(My water was tested yesterday at Petsmart and they said my water was fine). Yesterday my tiger barbs stuck together as a school and were very lively, swimming together around the tank. However, my gourami began hiding in the barrel decoration I have in the tank, which I was not sure of why. Then today, I noticed my Tiger barbs separated and are not swimming together, but instead are hiding behind objects like the heater and filter. I also noticed the Tiger barbs were making small, quick movements, almost shivering? Sometimes even hiding in the barrel with the gourami. What does this mean? All my fish are acting strange.I had my water tested yesterday, so I think thats fine. And the temperature in my tank is 80F.