Betta has a little bit of swollen eyes and has a little bit of straight silver lines on tail?
Yes tropical fish get sick in cold water. You need to monitor the temperature of the tank water. whart is the temp? it needs to be at or between 78-82 and it needs to be the same temperature 24-7 get a digital thermometer. Is the temp causing the symptons? IDK? pop eye is a sympton that can start from many causes. You need to keep the water clean and the tempurature up so that he can heal. I would add Seachums Paragaurd now, and to all new water to help him build a strong slime coat "fishy immune system" And I would add seachems prime after you test for ammonia, nitrite and nitrate.
What in God’s name are u talking about? Please cut back on the LSD