Betta Fin Rot and possible other diseases
 

Hi, I had been keeping my betta in a .5 gallon tank for 7 months, I had no idea how bad it was. About a week ago, I transferred him to a new 2.5 gallon Mini bow with a filter, heater, thermometer, gravel, cave, silk plant, and a gravel siphon. It's at 80º F. The hood has a 15 watt incandescent bulb, which I hope to replace soon with a fluorescent bulb. I have been changing the water twice a week, around 20-25%. We have well water from our tap with a filtration system, and I add NovAqua and AmQuel every water change. Each change I remove the decorations and siphon all the gravel. I feed him 2 Hikari Betta Gold pellets in the morning and 2 at night. His fins look pretty ragged and the very tips are starting to look different in color. He also looks somewhat dark, in a strange way, around the ridge of his back and head. He also seems quite lethargic, he will stay in one spot for around 1-3 minutes before swimming around a little more and finding another spot. Also, when resting on the silk plant, he seems to fall asleep and be pushed onto the leaf somewhat sideways by the filter current.
He seemed a lot healthier during the first few days he was in his new tank. Can someone please help me? How do I treat him? Also, since the tank is still cycling, is there a way to treat him without restarting or messing up the cycle?

I don't have my camera right now, but I will add pictures as soon as possible.

Some of what you describe sounds like normal behavior as far as sleeping against leaves and acting lazy, but the coloration changes are a matter of concern for sure. What's the hardness of the water you keep him in? Do you test for ammonia to make sure the filter is actually cycled?

Do you have a test kit to check ammonia and nitrite levels? Since you mentioned this is a new tank (and filter?) it sounds like your tank is still cycling. You'll need to do partial water changes more often (possibly daily) if there is ammonia and/or nitrite present. Once the tank is cycled weekly water changes will be fine. Can you post your ammonia and nitrite levels?

If the tank isn't cycled, I'd recommend changing the water 100% twice a week.