I have 6 tiger barbs, and one has been acting weird. They stopped schooling with the others and have just been sitting, facing a bit downwards and just kind of fluttering their fins. I've had them for two weeks and they were doing just fine until today. As the others barbs were swimming around, one tried to school with them and they ran away from them as quick as possible. I wouldn't think they're being bullied because they're the biggest barb in the group.