unknowen creatures in tank

Question
Hi,
i have a tropical fish tank, and today, just after cleaning it out, i noticed a few tiny thin creatures that look like worms. They are bout 1-2 cm long, and are white and brown. This is the first time i noticed them even though they could've been theres longer, and i noticed one of my baby swordtails eating it (well that's what i think it was doing anyway.)Do you have any idea what they might be and if they will harm my fish?? Thanks

Answer
Hello Kath,

The worms are Planaria. They are small flatworms that develop when there is too much food in the gravel.

My guess is your over-feeding the fish, and that it's gone into the gravel.

The tank needs cleaned, gravel washed out thoroughly and the planaria will disappear.

From now on, only feed enough that they eat it within one minute, once a day.  That usually is a very small pinch of food.

Swordtails love planaria.  Yum...and they don't harm them, however they are a sign that your tank is in need of some care, and water conditions suffer right after gravel does, so it's best to nip this in the bud right now.

Clean the tank, change the water, cut back on feeding. :)

I certainly want to extend the offer for you to write back anytime you want to followup on the question. :)

Happy fish-keeping!

Renee