Little white parasites on the walls of the tank

Question
Hi, I have these little white parasites stuck to the walls of my tank and they are multiplying very fast. They can be no bigger then a grain of sand or get a around 5 mm when stretching out while moving. They seem to be fixed on the walls of the tank and not swimming freely. I have a 44 gal tank that I've had setup for over a year withone oscar and one cichlid. The fish are around 3 years old. My little brother overfed them Wardley floating cichlid pellets while I was away. I came back and cleaned the tank and after noticed what I thought to be a cloudy mark by the fliter on the glass which I thought was just pour cleaning until the cloud also appeared on the side of the tank right by the back wall cloud. I took a close look and focused on a spec and I noticed it moving. It was gross. They move and looklike slugs. They are everywhere now in the tank after 3 days. They do not seem to bother my fish but I am worried and don't want to lose my oscar. What are these? Where did they come from? How do I treat the tank and get rid of them? Are they any harm to me cause I had my arm in the tank while cleaning? The only things I can think of was they were in the water I put in the tank which was from my shower, in the filter I put in the tank because I did not rinse it(but I never have) or leaving all the extra pellets in the tank. Thanks for your time to read my question and I hope you have an answer. Cheers.

Answer
Hi Glen;

They are some kind of nematode or planaria worm and are totally harmless to your fish. They are thriving on excess waste. They can't be killed by any kind of medicine or remedy. The little critters even survive bleach treatments after removing the fish to another tank. (I tried that) They have to be starved out. Overfeeding is what makes them really grow. There were a few in there somewhere that you didn't see but as soon as the fish were overfed they went crazy and multiplied. Make some water changes and vacuum the gravel to get rid of the waste they love to eat. Cut back on feeding for a awhile until they are under control. Your fish will be fine with just a minimum of food until this is over. The critters will just starve out. At first they may look like they are getting worse because they will come out of hiding to find more food. It's just a sign that they are desperate for food. Their hiding places became too clean.

To help you clean your tank easier you might consider one of the water changing/gravel cleaning units. At least two companies make them now. One is made by Lee and another by Python. They hook up to your faucet by a 25 or 50 foot hose. One setting will drain the tank, then with a twist of the plastic fitting you have attached to the faucet, you reverse the flow and refill it with tap water. Turn the faucet handles to adjust the temperature and it's so easy! Put your water conditioner in the tank before you refill and it treats the water instantly as it goes in the tank. I've used one of these gadgets for many years. Anyone with a tank larger than 20 gallons would greatly benefit from their use. No more carrying buckets!

At Your Service;
Chris Robbins