discus dead over night

[dean_alicia]

hey guys,

one of my dads discus died over night... its been a week in the tank and was fit and healthy. when we pulled it out of the tank its stomach was blown up to a medium size marble and was as hard as one too...
what could this be caused by....
its diet had changed from the presious owner as my dad feeds them a large variety of food.

thanks

[ILLUSN]

usually a tumour, but these occure alot more slowly, could also have been a blockage caused by too much high protein/high fat food and no fibre or just a heamorage.