My Oscar fish shake their tails and lip lock

Question
QUESTION: Why do my Oscar fish shake their tails at each other, lip lock and appear to bite each others sides? One appears to be more aggressive than the other.  The bigger one I estimate to be about 12 months old, the other about 10 months old.  They both live in a recently  bought 350 litre trigon fish tank wtih a cat fish which is bigger than they are with bogwood and rocks.
ANSWER: Hi Lee,
 It could be fighting or it could be courtship.  The trouble is the two behaviors look exactly alike.  The other problem is that male and female oscars look exactly alike.  The proof will be in the outcome.  If they are fighting, then the fighting will continue until one ends up beating up the other or chasing it around the tank nonstop.  If they are courting, they will suddenly stop fighting and will likely clear an area of the tank bottom down to the glass (or clear a flat rock) and then they may lay eggs.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>


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

QUESTION: If this is mating could too many rocks and bogwood in the tank hinder their progress?  There are some flat rocks in the tank and the temperature is around 78 - 80 degrees.  How empty should an Oscar fish tank be.  The Oscar fish and the catfish often uproot a plastic plant and move the bubbler disk.

Thanks for your help in my earlier question.
ANSWER: Hi Lee,
 Lots of rock and bogwood are great.   They will help not hurt.  

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>


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

QUESTION: Firstly, apologies for another question.  I am wondering what to do.  The 15 inch catfish gets his food put in the tank with the two oscar fish at the same time.  The oscar fish tend to eat all the food and leave him none.  Can he survive just off cleaning the tank or can I add another type of food that the oscar fish don't like?  The cat fish eat an oscar stick the other night from the top of the tank! he must have been hungry.  I'm amazed the oscar fish missed the stick.  I feed the oscar fish 10 sticks each, every morning and night and two pleco wafers for the cat fish at the same time.  Is my feeding regime incorrect?  Is my cat fish getting enough food?

Answer
Hi Lee,
 Put in the catfish food after the tank is dark (e.g., at night) and he will have a much better chance of getting it.  Oscars can't see in the dark very well, but the catfish uses his sense of smell and in fact would prefer to eat in the dark in most cases.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>