please help- betta can't move around??

[lise]

Hi All,
Just stumbled on this wonderful forum, and I hope someone can help. Our poor little betta, Sushi, a blue and red crowntail has had a tough run lately. We have just moved him into a bigger tank and put a heater in (his smaller tank was too cold for him) and he was happy, until I came home today and he was sort of just lying with his nose on the surface of the tank. The reason seems to be that his pectoral fins have shrunk. They used to be fairly big, but now they are very narrow and beating at a million miles an hour to move him around. I cant tell if there is any missing, or he just cant expand them. He did have a fin rot problem in his last tank, but we cleared that up, so I just have no idea what this could be, but he looks so miserable, not really moving around, not even really flaring up at his reflection. Can anyone suggest what to do? Poor little thing.. what have I done wrong now??
Oh, his tank was heated to about 82-86 but now we turned it down to 75 in case it was too warm. Would that have anything to do with it?
Thanks for any help.

 

[luxum]

I would keep him at about 80º, bettas like it pretty warm. You say you moved him to a new tank, is it cycled? Can you test for ammonia, nitrite, nitrate? The best general cure all for most fish is water changes. Try changing 20% of his water with fresh dechlorinated water every day for the next few days and see if he improves.