A couple of weeks ago one of my male guppies died, his tail became clumped together and he was unable to swim properly. One of my other guppies has just started showing signs of this today, however his tail is not as clumped together as much as the other guppy. Is this an infection or fungus and can i treat it? I have a few other male guppies and don't want those to get this aswell! Thank you.