Hi, I have a 10 gallon tank with 5 guppies (2 are fancy guppies). Last week one of guppies died, it was the day after I had done a 25-30% water change, not sure if that was the reason or not. Since then one of my other guppies has a large bump on its belly. I believe they are all males so I don’t think it’s pregnancy plus it doesn’t look like that. It is sort of staying to itself, sometimes laying on the bottom of the tank other times swimming around towards the back of the tank. The other three fish seem to swim around him and are interested in his belly. I noticed yesterday that he now has a red circle on the side of the enlarged belly. I tried giving him a frozen pea 2 days ago and he did take a couple nibbles. I have not seen him poop since then although I am not always watching. I don’t think it’s dropsy since no scales are raised. Not sure what else to do? Had the water tested at the pet store and the nitrate level was high but since I had just done a 25% water change I waited until today and did a 50% water change. I want to help him because obviously something isn’t right. I don’t want him to die, or be in pain or possibly infect the other fish. Can anyone help? Trying to add pics.