Worried about our betta

Question
We got our betta, Blueberry in August and had been keeping him in a 1 gallon bowl (changing water weekly) until recently. One week ago, I moved him into a 2.5 gallon Minibow Aquarium to give him some space and so that I could control the temperature a little bit better. The aquarium came with a Tetra Whisper Microfilter with Biobag and I am running it on the low-flow speed. I used aged (24hrs) tap water with Kent Marine Beta Bowl Essentials to fill the tank. I am also using a Hydor Mini (7.5W) heater under the gravel. The temperature of the water is pretty consistently between 78-81 degrees. There are two plastic plants in the aquarium as well as a small natural rock tunnel that he has loved. We feed him 5-7 pellets of Hikari Beta Bio-Gold daily.

I have not to date tested the water quality, nor have I changed the water in his aquarium. At some point today, he stopped using his left fin. There is nothing visible that would indicate any kind of fungus or rot.

My questions are:
- Is it possible that he injured himself? If so, what, if anything, can I do to help him.
- Am I doing right by him in his current set-up? What changes should I make?
- How often should I change his water and how much water should I change at a time?

I really am trying to do the best I can...just need a little advice.

Thanks!

Answer
Hi Melissa;

Unless there are obvious signs of infection there isn't much you can do. It is possible he bumped his fin or caught it something and it bothers him. Hopefully he will recover on his own. Fish usually heal pretty fast.

All tanks need a 25% water change once a week, every week. Vacuum the gravel too. There are very small mini-vacs with skinny hoses available for tanks as small as yours. I have one and it works great.

I think your setup is just fine. Just keep up with weekly water changes, don't overfeed and keep the water temperature consistent.

At Your Service;
Chris Robbins