Betta fish acting strange

Question
Hi Brittany,

I got my male betta in January and he has been absolutely fine.  He is currently housed in a 2.5 gallon tank with no tank mates and because the tank is relatively small, no heater either, (but he seems to be just fine without a heater).  I also do a water change every week.

Recently, however, he has started acting strangely.  I noticed that he's swimming about VERY fast, changing direction suddenly and sometimes even bumping into things because of it!  All I have in the tank are a few ceramic ornaments and some fake plants (though I was hoping to get some live ones soon).  

Is there a reason for his new behaviour and does this have anything to do with him building a bubble nest, i.e. is it just a case of him basically being 'sexually frustrated'?

Anyway, any help would be much appreciated.  Thank you.

Louisa

Answer
Hi Louisa,
This is normally the sign of a stressed fish. Try adding some more foliage for him, and change the lighting. There is a heater you can buy for a 2 gallon tank, it's a 7.5 watt mini heater by Hydor and you can usually get them at Petco for around 12 dollars. I would suggest getting one. The smaller the tank, the quicker the temperature will change, and quick changes in the temp can stress out a fish as well.