they are harmless. they are having a population explosion because you are doing something wrong. probably overfeeding but slack maintenance can cause their population to boom.
give your gravel a good vac and reduce the amount of food per sitting. it might also be worth giving your filter the once over, trapped food is a buffet for them.
as for fish eating them, i noticed you mention a jag. i think fish the size of guppies and rice fish eat planaria but nothing much bigger however its worth reading up.
give your gravel a good vac and reduce the amount of food per sitting. it might also be worth giving your filter the once over, trapped food is a buffet for them.
as for fish eating them, i noticed you mention a jag. i think fish the size of guppies and rice fish eat planaria but nothing much bigger however its worth reading up.