CichlidFish.com - Fish That Think.

I have 2 7"-ish Oscars. They are in a 55 gallon at the moment, but will be more comfortable in a 100+ tank soon. I'm not sure what their sexes are, so I put a piece of slate in the tank just incase. I've read other posts about sexing, and tried to follow it. My fish grew up together in wonderful water conditions, so according to the information I read on here (fish size, fin size, forhead size, ect.), I THINK my Tiger Oscar is a female and my Red is a male, but as I said, I don't know.

But on to the weird behavior:

My Tiger Oscar has developed an odd bump in her stomach, right above where she poops, right under her fins. I just noticed it yesterday, and it was never there before. She hasn't left the immediate area of the slate, and the Red Oscar has stayed constantly by the Tigers side. I saw her cleaning off the slate a little, and it was the first time ever but she never did it again. The Tiger has become a little more agressive with the Red. They have been mouth locking, tail slapping and shaking.

My Tiger keeps wiggling from side to side, and then she will dive to the bottom, sometimes hitting the slate or the gravel beside it.

They have done all this breeding like behavior many times before in the long time I have had them but nothing has become of it, so I figured they weren't male and female.

This has only been going on for 2 days, and I'm not too woried, just curious. Thanks for your help.

Time wil tell if she lays or not.. She should do so soon, when???  The tiger sounds like the female, but hard to tell really.. She could be developing the eggs now as the courtship stimulates her.. I hope you can see who lays the eggs, but it is probibley the Tiger.. Stillearnin is the Oscar expert here as he has/had pairs.. 

It sounds like mating play to me, but I have to keep in mind that Oscars are very dissimilar from specimen to specimen. Generally, if it gets a little rough and the two fish are about equal in dominance then it's mating play; if it gets rough and one of the fish is clearly dominating the other, it's simple aggression. With what you've told us, my bets are on baby Oscars. You'll need that 100+ tank! --Mark