Tetra acclimation

Looks like I might have a problem with the Tetras. One of the little guys is pretty active, but they don't stick together at all. Kate likes to wander around the tank, eying the site, but Lauren seems determined to stay in a little corner a couple inches away from the air filter staring forlornly at the wall. Some Internet research shows that the Tetras evidently like being in groups of at least five. I'm not certain my 1.5 gallon tank can support five tetras in addition to everyone else. If Lauren condition continues I'm left with either risking the little fishies' health or having to get some more Tetras and maybe having to get a fishbowl to put them in...which is pricey and leaves my aquarium without fish again. I'm hoping it's just a matter or getting used to the tank.