Fin Rot On My 1 year and a half year old guppy?? OH NO! :/
 

OK, today, I wake up to see my yellow guppy just sitting on the bottom of the tank.. Today, he has not swam up for anything but he has swam around the bottom of the tank. Recently, I have noticed little red dots on his tail and I noticed it was getting raggy at the end and I didn't think it was anything major at all. Today was his first day showing symptoms of just sitting there.. Idk how he also got it, yeah, I know it's been a while since I last fully cleaned the tank but the tank looks fine.. Temp is 78F and it's a 10 gallon. Btw, do you think he got this because he is older? I bought him in Feburary of 2010. Could it be because he could have a weak immune system because he is old? My red guppy and him play often and I did see some nipping every now and then but I never thought of it being major. I have 2 other male guppies in the tank, 1 female marble molly, and 2 cory cats. I have a feeling he could go tomorrow. :/

The tank may look fine, but that doesn't mean that it is! I would check your water parameters and do frequent partial water changes and syphon the substrate. Small tanks are less accepting than larger ones, water quality issues can arise faster and you have less time to rectify it. Fin rot is usually due to poor water quality and/or stress, if caught early enough can be healed by maintaining pristine water quality and addressing potential contributing stress factors. If he is being harassed, I would quarantine him.

Well, he sadly passed away this morning only minutes ago.. Poor little guy :/.. I will check the water, do a small water change, and change the filter.

Sorry to hear he didn't make it!