Hey Guys...

My two oscars (tigers) have been in their new home about a month now. They're about the same size (3.5"), with one being slightly larger (maybe robust would be a better word). As I have previously posted, when they both first arrived they swam side-by-side with the larger always leading the way. Their behavior toward each other was otherwise neutral. In the past week, however, I've noticed them in stand-off's; the smaller turning 90 degrees to the other and kinda vibrating it's fins quickly. They looked like they were kissing the other day. And finally, and what has me concerned, the larger guy is now chasing the other all over the tank. It seems to stop after I feed them and they seem to again swim in concert, but maybe, you guys can clue me in..

George

When the Oscar turns 90° to another fish, that is his defensive posture. I see that a lot in my tank. They don't do it to each other, they do it to the Jade Cichlid. There is a possibility he may have two males that just won't get on. How big is your tank? You need over 100 gallons really. Keeping more than one Oscar in anything less could lead to aggression problems.

I don't know. I have a mated pair and they get along splendidly and I haven't ever seen them fight. They are like peanut butter and jelly, milk and an oreo cookie, etc. etc. (you get the picture!)
They do sound similar as one is slightly bigger and more "robust" too but they just get along so well.

Possibly you have two males there in spite of the size difference.
Or it could be just some dancing before they make up and pair off (if they are male and female). In any event, I would only be really concerned if the fighting really gets bad and injuries occur.

Penn, Their by themselves in a 110 gallon. Plenty of room...

Thanks Ken