Last night I went to get my first Betta Fish. I have had the tank set up for a couple of days to allow the water to settle. The water is at the correct temperature, and has been treated. The tank is a 3 gallons, with a nice caved rock and 2 live plants in. The Betta is with a small group of tetras and a couple of shrimp. They all seam happy with no fighting, however the tetra has taken to just laying down on the bottom between the side of the tank and the rock. Is this normal? Should I do anything?!