Hi, Can anyone help me, i have just bought 75l tank, had it a few weeks now and have 4 ( 2 black, 2 silver - don't which are male and female!!!) mollies in and 2 honey gourmani, one of my silver mollies is quite aggressive and chases the 2 other black mollies around, when i take the silver aggressive one out the 2 black ones are fine and start showing all their fins which hasn't happened before, just wondering if anyone knows why they would do this ??? Any help would be really appreciated ! Thanks ??? ??? ???