Just bought my first fish (WCMM), got home to discover I had 2 extra, and 2 which look different to the others (and different to each other). May be tetra? I have an unheated tank so need to id them asap so i can find them a more appropriate home if needed. This the larger odd one out seems pretty happy, swimming around with the others. The one with the dark stripe is smaller and not moving about much.