I just bought a beautiful betta boy 12 days ago. Just two days ago i bought a new heater for him and a fizz tablet water conditioner (The original complete water conditioner in a fizz tablet. Each quick dissolving tablet makes water safe for fish by removing heavy metals, chlorine and by breaking the chloramine bond. It also adds beneficial electrolytes, promotes the natural slime coat and reduces stress). I cleaned out 3/4 of the water in his 1.5 gallon tank and filled the rest up with tap water and then added the heater (which i forgot to rinse off). I followed the directions for the fizz tablet water conditioner and added that in there last. When it stopped fizzing I added the fish into his new home. Also I noticed a few hours earlier the tank started fogging up but it went away a few hours later. I thought these changes would make him happier until I got home yesterday evening and noticed something wasn't right about him. His fins were clamped up and would spit out his food that i fed him. Every time i checked on him he would be either darting around like crazy or just laying there on top of the stones on the bottom of the tank acting like he was dying. I even put a mirror up to him and he didn't even notice it, before when i did that he would flare up at it. I don't know what to do?! I know it's obvious he's sick, but with what and how can I treat it and what precautions should i take to make sure it doesn't come back? I've shined a light on him and can't really notice anything different about him other than his fins looking all sickly clamped up and sort of raggedy. Please help me, I already love this betta fish, which i named Ike and would be devasted if he died this early. & I attached a picture of him when I first bought him, looking all healthy 
