I saw a chart on a web page a while back that showed various plant
problems and the cause. I can't remember where it was now that I need
it!!
That would be Chuck's page:
http://www.csd.net/~cgadd/aqua/art_plant_nutrient.htm
But I would look to the fish, first. Especially if you have loaches. They
like to bite holes in the leaves.
Leigh
http://www.fortunecity.com/lavender/halloween/881/