parasites in fish tank

Question
QUESTION: About 3 months ago we got the "ick". Unfortunately all of my fish died except for  3 platys and a fry of sunburst Mollies. I cleaned out the tank, treated it for 2 weeks, and gave it an additional 2 weeks to make sure everything was dead. I put my fish back in about a month ago and started letting algae grow on the back wall so we could re-introduce a pleco into our tank. Last night as I was cleaning the front glass of the tank, I noticed what looked like swimming sand granules in my tank. They were clustered all over the back wall of my tank where the algae is growing. There were THOUSANDS. I freaked and pulled all of my fish into the quarantine tank, did a partial water change and managed to deplete the population down to a couple hundred. They live in the gravel too. They're about the size of a large grain of sand. light brown, and they stick together. I've seen a few as large as a lice egg. They're all visible to the naked eye. I'm going to attempt to treat my tank with an anti-parasite medication, and may treat my quarantine tank as well to be safe. But I would like to know just what I'm dealing with and how to prevent this in the future. I'm not a fan of having to medicate my tank every couple of months and we haven't introduced a new fish into our family since before we got ick. Any help would be welcome. Thank you.

ANSWER: Danielle,

Don't panic.  You have a VERY common Planaria (flatworm) infestation.  They will be from round to elongated, and they do stick together.

This is planaria.

Planaria come from overfeeding and overcrowding.  From dirty water.  You should have NO algae.  Algae can only form in poopy, dirty water.  Not sure how this can be, having no fish in the tank, but if you did have fish, there are 2 issues at hand, causing both the algae and the planaria.

First, you don't need to grow algae for the pleco.  Feed him pellets.  This means you can keep cleaner water. :)

Secondly, the filter needs changed monthly, with new media.  Simple washing doesn't do.

Water quality being perfect, you won't have planaria or algae growth.  Algae growth is a bad thing, and it means the water is dirty.  Algae eats poop and lives off of poop and lighting.  Remove the poop, and it won't grow.

If you have any, the tank is not properly being maintained.

Planaria will disappear once overfeeding and overcrowding are ceased.  They come from an abundance of food.  They are a natural occurance, which can be stopped by simple changes in how the tank is maintained.

Again, it goes back to maintenance.

Let's take a look at proper feeding. :)  Proper feeding means feeding fish only what they can eat and devour entirely within 1 minute.  No food should ever hit the bottom.  Plecostamus get pellets of algae.  They are affordable, about $5 a bag, and you can feed him a pellet everyday.  If he's small, give him a half pellet.

Planaria will disappear once these things are taken care of.

Doing a water change is a great idea.  Instead of a monthly change, as some people recommend, I do recommend a bi-weekly 25% change.  Keeping water clean is essential to a good tank.

Don't panic. :)  You're a good fish mom, Danielle, and your tank will recover from Planaria.  Some fishes actually enjoy nibbling the little nasty things.  Yuck.  

They are normal...they do pass fast.  Getting them down to a low roar was a good idea.  Good move.

Happy fish-keeping.

---------- FOLLOW-UP ----------

QUESTION: I forgot to mention that after the month of treating and getting rid of the ick we DID put our fish back into the tank. Ive been feeding them once a day to avoid over feeding but the algae grows so fast that we've talked about investing in some shrimp or a pleco. I do have the algae wafers, but was told they prefer alive algae? And as long as these critters arnt going to hurt my fish, Ill let the tank do a cycle for a day and put my babies back in. Do these things just appear, or are they always in my tank? And should I think about adding more fish then the 10 we have (55 gallon tank), and what would help keep the pest population at bay? Thanks so much.

Answer
Hi again!

Keeping them at bay is easy.  Super clean water.  Double up on filtration.  Light feedings...never overfeed.  They do exist in tanks, but populate upon high food times or times of severe fish waste.  The little boogers love that stuff.

No worries...again, perfectly normal. :)

Algae = bad.  Pleco = bad.  Here's why.  The pleco is a heavy pooper.  His feces are going to do more damage to your tank, than good. Get Chinese algae eaters. Although not as cute, they are expert algae eaters.

I use Nerite snails to eat algae.  Not a speck left.  Try to find some.  They're wonderful at it.

In a 55 gallon tank, you can probably get away with a few more fish, but it depends on how many you have now.  Try to stick to 2 inches of fish every 5 gallons.  That's a good indicator as to how many you can have.

I hate rule-of-thumbs like that, but they really do help you keep a good idea.  

Also keep in mind, to properly filter a fish-populated tank like a 55, you might consider doubling up on filters.  I use 2 marineland 350 filters in mine for a small fish population.  I clean water bi-weekly.  This keeps the tank sparkling clean.  I have fish die, like everyone else, but mine die of old age only.  You might keep that in mind. :)  It's worth the investment for years of enjoyment, rather than years of frustration with water quality issues.

Happy fish-keeping! :) Write anytime.