Betta Fish is sick

Question
I have had my betta Zeus for about a year and a half. I have him in a 2 gallon tank, by the sun. I don't treat the water or have a filter. I have a container I let sit for 48 hours full of water for changing, which I do about every 3 weeks. Zeus has always been very active and eats well. I recently changed his tank. I take him out and put him in the little bowl he came in, clean the tank with water and put all the same rocks, plants, and castle back in.
This time when I put him pack in he kinda floated to the bottom, with his head pointing up and tail down, on a diagnal. He is not swimming, he just lays on the bottom and won't eat. It has been three days and no change. I put food in the tank and he doesn't swim to the top. I go near the tank and he doesn't move. He just sits under the castle. I'm afraid I injured him or something...I am going to try to heat up the water with a heating pad after reading some of your other responces. Thanks :)
Please help...

Answer
Hi Nicole;

Poor Zeus. He has gone into shock for some reason. Warmer water will definately help. He needs his water changed every week too. After three weeks in his bowl the old water is so much different in composition that it is a shock to his system when it is finally changed. You might consider a water conditioner too. Good ones like Stress Coat, NovAqua, and Prime will help the fish with shock and remove chlorine, chloramine and metals too. Letting the water sit out is very good, but only the chlorine is going to evaporate. The rest of the harmful stuff could still be in there. Just use fresh tap water that is the same temperature as his warm bowl water and use the conditioner. I think it will really help.

He is going to be more sensitive now too because he is getting older. Betta lifespan is 2 to 3 years and they are already about a year old when you buy them. That makes Zeus about 2 and a half already.

Hope he feels better soon....

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