Abnormal Fish Behavior?

[DirtyHarry]

I've noticed this for the past week, my red bellied pacu has grown to about 7 inches in my 55 gallon (yes I know 55 gallon is too small) and just recently he has been swimming frantically up and down back and forth the tank for hours on end. He wont eat anything at all and my 2 blood parrots, pleco, and pearl cat spend 90% of their time under the same rock. Any help please on what's going on because I've never seen this kind of behavior before.

 

[annka5]

I know very little about pacu, but a general fish-wide thought would be that the reaction to me could be due to:
1) Water quality issues, trying to "escape"
2) Over crowding - as above
3) Boredom (?)
4) Enthusiastic begging for food

I'd start by trying to figure if there could be anyhting wrong with the water- test for pH ammonia, nitrite, nitrate; try to think of any way chamical could get into the tank, when you last changed water, etc.
Over-crowding - can't comment as don't know how much space your fish need - don't know enough about them - activity levels, need for territory, etc.

 

[DirtyHarry]

Water quality is normal and I disconnected heater. Still no change. I think my pacu just wants out. There is no interest in food but he appears very healthy and full of energy. And as for the other fish I think they are all hiding because of all the movement from the pacu being as he is 5 times their size. I may end up giving the pacu to my friend with a 180 gallon.