Hi, i have a 10 gallon tank that has been up and going for about a month now and the fish have been doing great until now. I have 5 small fish I have just noticed my pleco algae eater and a guppy losing their colour drastically. We think one of the small fish (cant remember the name: it has purple zebra stripes) has been nipping at the guppy's tail and others and he has now been separated, could that be the problem? I have tested the water and everything is fine and the temperature is good for all of them. I have cleaned it once a week by removing 25% of the water too. Any help would be great! I dont want to loose any of them. Thank you!