i have a 12 inch albino oscar, he is in a 180 gallon, with 2 plecos a 8 inch florida gar. and 2 16 inch ID sharks, He is really calm and doesn't bother anyone the more i read the more i see how he should be more aggro and not be in the tank but he is completely calm and just minds his own, could he be sick is this normal? or is he just a chill guy?