Originally Posted by Vera
I got a rescued betta during the summer. He was fine and even adapting to cooler temps at nite. I usually do a complete water change when I clean his tank. Last week I got another betta & put it in a bowl INSIDE his tank for company. In the morning both fish were dead! They didn't seem stressed. Got ANOTHER betta, after changing water, and he was dead within the hour. I bought a mini heater (my tank is about 2 gallons) but it seems useless. I use reverse osmosis water I make for my salt water tank so it's cold from sitting in buckets. Am I better off using warm tap water & putting conditioner in it? Also, should I be doing a COMPLETE water change? Never had a problem all these months, but then, it was summer. Now the nights are getting chilly. Tyson was my 1st & I really miss him. :( thanx! Vera
To simplify I’m going to name the Betta’s. Alpha (1st), Bravo (2nd) and Charlie (3rd).
I wanted to clarify something. You purchased Bravo and placed it inside Alpha’s tank? Male Betta’s will fight and die if in the same water as each other. If you have 2 Bettas both will require their own separate tanks.
Charlie may have passed because of conditions at the pet store or an existing disease. It is also possible that the Bravo had a disease that killed Alpha if they didn’t fight. This disease may have lingered in the tank and killed Charlie.
I would recommend purchasing an internal suction thermometer to properly measure the water temperature, it may be too hot or too cold. Without the thermometer, we won’t know how effective your mini heater is.
Depending on what the levels of your tap water is (ammonia & pH), you may find it easier to use tap water and add conditioner. I am unfamiliar with osmosis water and Bettas, so someone with experience may comment to assist.
For the water change questions, are you using a filter at all?