Hi, I just got sold a couple of German Blues yesterday and was promised that they were a couple. They are close by most of the time, but then the "aggressor" pushes the passive one away. The passive one runs and swims up and down the glass on my 60 gallon tank. The aggressor prevents the passive one from digging/eating sand next to the plants. The aggressor also seems to have a bad fin, should I be worried about it in your opinion? I am allowed to trade them for other ones if I wish but I would have to do it within the next week. The store told me that these two are paired, and they are almost always close by. Maybe the passive one is still stressed, and the other is trying to get there attention? They are trying to kill my Malaysian Trumpet Snails, will pick them up and shake them I feed them frozen foods, live Daphnia, and 3 different dry foods and still need to get some worms. Any tip or information is appreciated. They live with Ottos, Chillis and some Shrimp. Thanks for any help you can offer!