Undergravel Filters/Oscars

Question
We have a 55 gal. tank with 2 oscars.  We just bought an undergravel filter for the tank.  Everything is hooked up, but I just want to make sure that it will work properly.  There are four tubes coming up the tank producing bubbles.  Is this really cleaning our tank?  Do we need to clean the tank any differently?

Also, the water in the tank gets very green like algae.  We have tried algae eaters, drops, etc...nothing is working.  We also see small worm like parasites producing at the same time.  Do you have any advise on what we should try?

Our Oscars are always moving the rocks around.  Is this normal?  Why do they do this?

Thanks for your time.
Michelle

Answer
Hi Michelle;

I hate to say it now that it's done, but undergravel filters are not suitable for larger fish like oscars. UG's are fine for fish with smaller wastes like tetras, platies, barbs, etc. It might be okay for a few weeks if the oscars are still babies, but not for long. Undergravel systems are biological filters only. Oscars require mechanical filtration. Oscar waste is too big for UG so the gravel becomes impacted in some areas and the oscars dig it up in other areas. Too much flow occurs in the shallow spots and none occurs in the impacted spots causing very dangerous fouled waste accumulation in those areas of the bottom. Oscars and other big fish also break the lift tubes loose. They will try to swim behind them between the tank glass and the tubes and continually pop them loose from the base. Then, gravel falls inside the hole causing even more problems with flow. For fish like yours you need a power filter, or even two. It provides actual mechanical filtration, which is necessary for big fish.

The little white worms you are seeing are planaria. they are harmless to your fish but are a sign of overfeeding. They are thriving on the excess waste being provided to them. To get rid of the excess waste, which is the REAL problem, vacuum the gravel once a week while removing 25% of the water. Also cut back on how much food you feed by 1/3. Eventually the planaria will disappear. What you don't want to do is use chemicals or medicines to try to kill them. They are tough little devils and will survive treatments that kill your fish. Besides, they are not the problem. The excess waste is what is dangerous. I really think your algae problem will go away on it's own once the tank is cleaned up.

It is normal for oscars to move the gravel.  They are trying to make holes to spend their time in. They like to "redecorate" to make the tank more to their liking. They do it all the time and may change digging spots from time to time too.

It sounds like you need to know more about oscars and their care and maintenance. Here are some sites to help you;

http://www.cichlidfish.com/oscars/OscarTanksetup.shtml
http://www.aquariacentral.com/articles/oscar1.shtml
http://members.tripod.com/~oscette/
http://www.theoscarspot.com/index.htm
http://www.cichlidfish.com/oscars/oscars.htm

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Chris Robbins

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