ArnieStinger
Fish Fanatic
The puffers are semi-brackish fish and your very hard water is probably helping them survive without the salt. The betta splendens is definitely not a brackish fish but mine have shown a huge ability to adapt to differing tap water conditions. As long as you have only one tank, fish that different in their needs will be asked to adapt quite a bit.
You're right. I think the fact that the betta is breed from london and it's last owner was 3 or 4 miles away would mean that the water would still be very hard, the betta and the puffers are probably well adapted by now, I think they are at least a couple of months old, if not 7+? Long enough to adapt or perish I would think.
Im 100% sure the water conditions are better than their last tank, the last owner did not use salt, a filter, clean the gravel or change the water often.