Stefanie, I’m glad to read that your new betta and paro-pairs have survived their unlucky travel. They are both rare, and beautifull as well.
Your experience reminds me of a situation that occurred with my 60l. tank last week.
It’s habitants, 5 P. bintan were schooling together. I wondered why they were acting so peacefully. Not really their style, as they used to behave very territorial.
The next evening, they still moved together in group, along the front glass. I became suspicious as they didn’t show any interest when I offered them artemia for supper. I started checking the water quality. This way, I found out that the heater didn’t function any more. The temperature had dropped to 17-18 degrees. A spare heater helped to solve the problem. I’ve already bought a new replacement heater.