I bought 5 rosey fin tetra (labelled white fin rosey tetra in some shops) yesterday for my 138 litre community tank containing 5 guppies, 4 albino cories and a bristlenose pleco and acclimatised them for about 45 minutes last night (I don't have a QT tank unfortunately) they were very nervous last night and were sticking together in a group shyly exploring the tank. This morning they seem a lot more comfortable (although still nervous when I walk past obviously) but as I've been watching them today they've been chasing eachother like mad. I haven't seen any fin nipping, just darting up to eachother so the other one shoots off. They're doing it loads. Not sure if its aggressive or just playing? I've tried to attach a video but obviously as soon as I got my camera out they stopped doing it so much lol. Also is 5 a good number to have? I thought that's what I'd read. Thanks