Tank size: 14 L Q/T, became sick in 30 litre divided
pH: 7.8 (hard water area, this is stable)
ammonia: 0
nitrite: 0
nitrate: 10
kH: Hard
gH: Hard
tank temp: 27C
Fish Symptoms (include full description including lesion, color, location, fish behavior):
Acute lethargy, heavy breathing, fairly unreactive to surroundings, tattered fins (but no signs of actual fungal or bacterial finrot), erratic movements. No loss of colour, as far as I can tell, but he's white so . . . The only weird thing I can think of (apart from the usual "ugh, I feel ill" behavior) is that he has tiny holes in his head. I can't work out if they are meant to be there and you just don't see them on coloured fish, or if these are bad. Some are larger than others and they kind of look like pores - quite natural and smooth.
Volume and Frequency of water changes: 25% a week, more in Q/T to maintain freshwater flow
Chemical Additives or Media in your tank:
Biological and chemical media only, some aquarium salt
Tank inhabitants:
None in Q/T, another betta in divided tank. Other betta seems fine, apart from the fact that he (like all my bettas) has managed to tear his fins. They all do it - every single betta I own manages to get tatty fins within a couple of months. I have no sharp decor - just smooth caves and silk plants. How do they do it?
Recent additions to your tank (living or decoration):
I set up the entire Q/T tank recently so put all the decor and gravel in from storage. All was washed and sterilised before being added. In his proper tank, the only new addition was the other betta but I've had him for a couple of months (or longer) now and he seems fine.
Exposure to chemicals:
Unknown
pH: 7.8 (hard water area, this is stable)
ammonia: 0
nitrite: 0
nitrate: 10
kH: Hard
gH: Hard
tank temp: 27C
Fish Symptoms (include full description including lesion, color, location, fish behavior):
Acute lethargy, heavy breathing, fairly unreactive to surroundings, tattered fins (but no signs of actual fungal or bacterial finrot), erratic movements. No loss of colour, as far as I can tell, but he's white so . . . The only weird thing I can think of (apart from the usual "ugh, I feel ill" behavior) is that he has tiny holes in his head. I can't work out if they are meant to be there and you just don't see them on coloured fish, or if these are bad. Some are larger than others and they kind of look like pores - quite natural and smooth.
Volume and Frequency of water changes: 25% a week, more in Q/T to maintain freshwater flow
Chemical Additives or Media in your tank:
Biological and chemical media only, some aquarium salt
Tank inhabitants:
None in Q/T, another betta in divided tank. Other betta seems fine, apart from the fact that he (like all my bettas) has managed to tear his fins. They all do it - every single betta I own manages to get tatty fins within a couple of months. I have no sharp decor - just smooth caves and silk plants. How do they do it?
Recent additions to your tank (living or decoration):
I set up the entire Q/T tank recently so put all the decor and gravel in from storage. All was washed and sterilised before being added. In his proper tank, the only new addition was the other betta but I've had him for a couple of months (or longer) now and he seems fine.
Exposure to chemicals:
Unknown
/en.wikipedia.org/wiki/Head_and_lateral_line_erosion
he seems able to balance when he swims up for air but his movements are erratic, although I'm not sure this ia boyancy issue. 
