What Sapphoria said, how long did your office fish live? I can tell you in proper care I have had betta's live 7 to 8 years. Small tanks need to be cleaned every other day period. They need heaters period. It's just apart of caring for these tropical fish. Just because they survive does not mean they are healthy. I am sure they have clamped fins from the cold and poor coloring. As you see ammonia build up is no joke, it kills fish especially betta's who are very sensitive to it. Filters help keep water clean longer but even I have a 5gal tank and do 50% water changed twice a week on Sundays and Thursdays with a filter in it. (I'm also cycling the tank with the fish in it right now so once that finishes it will be once a week) That is just proper fish care my friend. With betta larger homes are better, if you keep a small one change the water frequently. They need heaters, they must be in water 78 to 86 degrees. These are topical fish not goldfish, they don't need a filter but filters help keep water clean so a light filter is always nice, they also need hides, foliage, plants living or fake to hide among, and they need a dark period where the lights are all off. Lights on them 24/7 is stressful.