Parasites, i think.....

Question
Hey!
I have an Oscar, she's about 2-3 yrs old.  I noticed over the past few days thats she's been really lazy, either floating close to the top of the tank, or bottom.  I took a good look at the tank, and noticed that there are these little tiny white worms crawling all over the sides of the tank, and all over my fish's body.  I don't know what this could be from.  We feed her only feeder fish from Petland, and im wondering if they came from there.  My main concern though, is what are these things? how do I get rid of these? Are they harmful to my fish?  Are they able to crawl out of the tank, or prefer water?  I was thinking of taking the fish out of the tank and cleaning the log, plants, rocks and tank with boiling water, but honestly i dont know anything about fish and dont want to stress her out too much! HELP?!
Thanks
april

Answer
Hi April;

I would suspect your tank has become infested with nematodes or planaria that are thriving on excess waste. They are actually a sign of overfeeding. Her lethargy may be from bad water quality that also relates to excess waste. These types of organisms live anywhere there is water and only overpopulate when there is an adequate food source. They can't be killed by any medicine or even bleach though. They have to be "starved out" by the removal of their food source. I have never seen the waste-feeding type on the fish themselves and they don't normally harm the fish at all. They may be feeding on her slime coating while she sits on the bottom where they are closer. They can't live outside of the water so don't worry about that.

Stop feeding her for a week and do some cleaning. She will not starve so don't worry. Fish don't need to eat daily and larger types such as your oscar can actually live fine for 3 weeks with no food at all. It's for her benefit right now and may save her life to fast for a few days. Replace 25% of the water every day and vacuum the gravel for one entire week. The vacuuming will draw the waste along with many of the critters out of the system too. Pick up the decorations and clean under them as well. Partial 25% changes daily will help avoid excess stress for her. Too much water removed in one day could stress her or even kill her. You may see more of those little critters at first because they are getting desperate for food. They come out of their hiding places looking for more. They will eventually fade away as they starve.

I don't usually recommend a "total" cleaning of any tank, especially with large fish. It causes the tank to break-in all over again and that can be deadly for a tank with a full population of even smaller fish.

Before I knew what they were several years ago I tried to kill these things what I too thought were "parasites". I had another tank to put the fish in so I didn't need the infested one right away. I took the fish out, put into the tank a cup of bleach, let it circulate through the filter for a few hours and drained it all out. I refilled and drained a few more times and finally let it refill and circulate so maybe I could use it again in a few days. Two hours after I refilled it for the last time....several of the little critters were still alive in the gravel in there. They are CRAZY hardy. They aren't harmful but I didn't know that at the time. The point is, don't try to use chemicals or medicine to kill them. It will only cost you more money, disrupt the bio-filtration, isn't necessary and stresses the fish.

I don't recommend giving any fish live feeders unless you have fish that require live food and absolutely refuse pellets or other commercially prepared foods for 10 days. Most fish will switch foods when you don't give them what they are addicted to for a week or so. Feeder fish are seriously stressed so they carry disease and are not very nutritious once they get to your home. Over a period of time your fish can develop malnutrition and become ill very easily. They just don't get the nutrition they need to stay healthy. Here is a link to an article that discusses the reasons why they aren't a good food;

http://www.wetwebmedia.com/goldfshfd.htm

I hope things get better very soon. Let me know if you need more help...

At Your Service;
Chris Robbins