Thanks for your comment, but I don't think you read my response correctly. I said that when I clean the tank, I only dispose of 50% of the old water, and keep the other 50% to add back to the tank after cleaning for the purpose of keeping the good bacteria. For one, I live in a small place and do not have much room for anything bigger than a half gallon, and for two, I have never had an issue with previous bettas. They had either died from old age and I gave one away due to moving towns and not having the time to care for the fish because of my new lifestyle, one having lived as long as 6 years in his .5 gallon tank. I do believe that your guide is useful and has some helpful tips, but I don't think it is detrimental to the fish to have a smaller tank based on my experience. I am not a "newbie" betta owner; I have had a few bettas in the past and have had this one for months now with no issue, and no routine change. She has never shown signs of stress such as colour change or not eating. She is a very lively fish who I can promise you is well taken care of. My betta is not lethargic; if she did become lethargic then I would make a note of the water temperature as that is a sign that the water is too cold. However, she is happy as can be, and I would prefer not to stress her out by changing her living conditions now as she has lived quite some time in that temperature range, which is actually a recommended range on some betta guides other than yours.

One question, however, because you do have me confused on this one (I have never used a filter with previous fish and they did just fine). We can both agree that betta's prefer as little movement in their water, correct? So why is a filter necessary, if it would only stress them out? I will make a note to increase water changes, but I really was hoping more for an answer as to what the growth on my betta's fin is.