The aquarium is 120x60x45cm/48"x24"x18" (LxWxH), approximately 300 litres, bare-bottom wood only. Filtered by Eheim 2180, 2128 and 3451. It has been running for almost 4 years now with this fish. Water parameters (long term): pH 6-6.5, gH 4-6, kH 1-3, NO3 10-50mgl.
Water changes are usually a minimum of 2 x 30-40% per week with treated tapwater.
It was suggested to me that phosphates could be the cause, and they tested at 0.5-2mgl, but I'm not confident about these results. NO3 today was 10mgl.
The first photo is from April 2012. This is what 'historically' the teeth and jaws looked like.
![Image](http://i186.photobucket.com/albums/x55/matthewfaulkner/P1070968_2-2.jpg)
The second photo is from April 2013. This what they look like now.
![Image](http://i186.photobucket.com/albums/x55/matthewfaulkner/DSCF2360.jpg)
The behaviour of this fish has changed, but I don't know when this happened exactly due to being away at university. Rather than typically resting/hiding under wood, he now rests in the open, attached to the large internal filter. There is less general wood detritus in the aquarium, harder vegetables like carrot (which were previously a favourite) are ignored. Outwardly appears healthy, eating mainly Tropical (brand) spirulina granules and sweet potato.
Can anyone offer any advice or help?