Hi, I hope someone can help work out why my cardinal tetras won't come out from hiding at the back of my tank. I have 15 very active harlequin rasboras that swim all over the tank but mainly the middle to top of the tank. There is 6 cory that just stick to the bottom as they should doing there own thing. There are 5 galaxy rasbora that swim around quite happy but the 10 cardinals hide amongst the plants very rarely venturing out. The fish have only been in the tank 7 days 2 died but were replaced by the fish store. Ammonia, nitrite is 0 nitrate is 10ppm ph is 7.0/7.2 the tank is heavily planted with lots of hiding spots which they seem to be using. I was wondering if the harlequins were just too boisterous I haven't really seen them come out much for food either. If you need any other info to help let me know. Thanks in advance to anyone who can help me get them mixing with the others.