I have just started noticing that two of my three male guppies poop have been red. I know that it is common for poop to be different colors depending on the food, and some of the food that is given to them is red. But my problem is that it stays solid and sits at the bottom on the tank, is this normal? I have looked for movement in case it is worms but I have not seen any yet. As I said, I have only seen 2 of my guppies pooping like that, I haven't seen the third. This has only started happening about 3 days ago. What should I do?