Hopefully your fish will survive, if so you should look for a larger tank, glow light tetras need plenty of room to swim and are also shoaling fish that need at least 6 fish to shoal properly. They are also a soft water fish. I live where the water is moderately hard so I reduce the hardness with RO water to have a healthier environment for my tetras. I have a 55 gallon soft water tank where I keep my shoal of 14 glow light tetra along with several other shoals of tetra. You do not need a 55 gallon tank but a larger tank like a 20 gallon long would be much better for them.