My Oscas behavior

Question
Hi.  I have two Oscars that I keep in my 40 gallon tank.  Regrettably, i bought my smaller Oscar about 6 months ago and i did not do my research on what kind of environment he needed.  I kept him in a 10 gallon tank that did not even have a heater.  He barely even grew in the first 5 months when he was in the tank.  He is now in a nice 40 gallon tank with a new buddy and as soon as i have the money im getting a 125 gallon.  My question is i have noticed some strange behavior and im wondering if it is ok.  Sometimes when he is feeding or just swimming my the filter he does random flips in the water that are impressive but i am concerned.  Is this normal behavior?  Is it playing or is this something bad?  Also, is it ok that i place both of my oscars in a ten gallon tank for the 15 minutes that it takes me to completely clean my 40 gallon tank once a month? I usually clean gravel, tank, and all once a month and 50% water changes weekly.  Is earthworms from right in my Indiana backyard a good occasional treat?  What is better, sand or gravel?  Are live plants worth it?  Sorry i have so many questions but i am trying to redeem the misuse that i had with my first oscar.

Answer
Hi Patrick,
 You should not place the fish in a tank while you "completely" clean the larger tank because you should never completely clean a fish tank. Doing so disrupts the natural bacteria in a tank that keep it healthy.  If you completely clean a tank, then you are in essence starting a new tank over and that takes about 6 weeks for it to balance out.  It is MUCH  better to clean a tank partially more often than in a big clean less often.  50% water changes are about the maximum I would do at once. Bottom line is that you shouldn't disrupt a tank so much that you feel the need to take the fish out.

 Earthworms are great.  

 Sand or gravel is entirely up to you.  I wouldn't put live plants in with an oscar because the oscar will tend to tear them up.  I use plastic plants with all my larger cichlids (and the cichlids even destroy those).  

-- Ron
  rcoleman@cichlidresearch.com
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