I have a 10 gallon tank with a 20 gallon filter and an under-gravel filter. I currently have 4 rosboras and 2 otos and they are all doing fine. I was wondering if I could add a couple more fish to my tank to add more color. Would fancy guppies be a good choice? I am having trouble deciding on what to do, so if anyone has any advice it would be greatly appreciated. Thank you in advance