I changed tanks and my betta is freaking out

Question
I just changed my betta fish from his old and really tiny flat tank to a larger round tank and after moving him he seems to be gasping for air. His little fan around his head that comes out when he sees other fish keeps going in and out. The old tank was small and had pink rocks in the bottom, where as the new tank is larger and has rainbow colored rocks, a treasure chest, and a plastic plant. I let the water get to room temperature and a added a little bit of his old water to the new tank for bacteria. I know he hates going into his net, but otherwise I couldn't get him in tank, however I have never seen him act like this. I am very worried. Before changing him into this new tank about three days ago I came back from vacation and my friend I had left him with was not good to him at all. I came back to find his tank not even half full and very dingy, he also looked much thinner and his beautiful bright pink and lavender shade had faded to a hideous brown. I immediately cleaned his old tank and fed him and much of his color has come back. I thought this new tank would make him feel better, but I think it is really freaking him out. Here is the problem though, I cannot put him back in his old tank because after seeing him so disturbed I rushed to get the old tank and tripped, causing the tank to break on the concrete floors of my dorm. Have I caused him too much stress? the water purifier has stress coat in it. . . Does he feel he cannot adequately guard his new larger tank? I know you cannot read a fish's mind, especially one you haven't met, but I would really like some advice on the situation. You know something telling me what I can do because as of now I have stayed up an extra 45 min when I have a test first thing in the morning, just because I don't want my little friend to die. PLEASE HELP!

Answer
Hello Chanese-

It seems as though you have done everything correctly: You added water purifier, stress coat, and let the tank water get to room temperature before introducing your betta, right? It was also a good idea to add a little bit of old water.

Did you wash off the plastic decorations and the gravel before you put them in the tank? Sometimes they can have a weird smell (usually caused by packaging) that comes off in the water.

It's normal for fish to breathe fast when they are transferred into a new environment. Your betta should calm down in an hour, but if he is still breathing fast you should remove him and put him in a small plastic cup, and wash out the tank and decorations with hot water (no soap.) Then you can put new water back in, and be sure to use the water purifier. Float the cup your betta is in until both the bodies of water are the same temperature. The release the betta.

I hope this helps, and good luck on your test
Amber Worman