Hi, my name is Caroline and I have a classic butterfly male beta. I have had him for about 2-3 months now and everything has been perfect. He has a hiding spot, tall grass plant, leaf hammock, filter, heater, and marbles for his base, all within a 3.5 gallon tank. His behavior has been very happy but I added some decor and did a full water change 2 days ago. Ever since he has been spastic (which I thought was normal cause he has always been a fast swimmer), but he is finding a spot where there is less marbles and acting strange in the area. It is hard to explain but it looks like if a beta fish could dig or is spazzing out or is swimming super fast but is already at the bottom so he is going nowhere. I got an ammonia testing kit and it said the water was fine, and I also put water conditioner when I clean his tanks. After I took the test I put in a “stabilizer” that said is completely harmless to the fish just in case. It’s worrying me and I don’t know if there is anything I should do.