Well, I had initially purchased a 3" O from my LFS, but today I got a call saying someone traded in a pair of fully grown Oscars and they cut me quite a deal so I swapped out the little guy and filled that 75 gallon right up. I am still debating taking the male back (the common O, I checked his vent before he went in, and I'm pretty sure the other is female from glimpses of her vent in the tank) because it is only 75 gallons after all and I don't know what I would do if they laid eggs. That, plus now I really have to go out and pick up a second canister filter for the tank since one XP3 probably won't cut it anymore.

Here's a video I took of them this evening, a few hours after I placed them in the tank:

Ok. Here are you trying to say that you determined the sex of the oscars by looking at them? Because this is impossible, the only way to tell their sex is when they are mating.

And you said you went home and filled the tank right up, does this mean you didn't cycle the tank? If not please read oscarfishlover.com/helpful-articles/cycling-an-aquarium


Cycling the tank is EXTREMELY important and you will likely lose fish if your tank is not cycled before adding them, especially full grown oscars, because they produce so much waste, which breaks down into highly toxic ammonia. You may want to consider getting the beneficial bacteria from another source, such as existing tank media. If the tank is already cycled then ignore my babbling, if not, please read the article and it may be necessary to take the fish out until the tank is cycled, they may live through a cycle but it is very stressful for them and very likely to kill them.

I sexed them by checking their vents while gently handling them from the bag to the tank. What I saw was compared against this image:


By "filled up" I meant stocking, not actually filling it with water.

As for cycling, I am using ceramic rings from the filter on a cycled tank in one of my canister baskets and just for an extra boost I used an entire bottle of Tetra SafeStart. Ammonia is 0, Nitrites are 0, Nitrate is barely a shade below 10ppm on my chart. No worries, I'm aware of the nitrogen cycle and will be watching parameters closely over the next week. As I said, I'm not sure two Oscars is such a great idea due to concerns over water quality and how quickly it can degrade with two messy fish. I'm likely going to return the common O, sadly.

Thank you for the concern however!

Ok good on the cycling, I didn't mean to come off as an ass, I was just making sure that the oscars weren't in any danger

As for the sexing, I am not aware of a way to sex oscars by just looking at them, and I think I speak for the vast majority of the people on this site, when I say that. That is usually the general concensus here. Although the pictures you posted are interesting, and something to think about...

And I would have to agree with you that one oscar might be better, 2 is a bit much for a 75g.

some people say you can vent to find the sex of your oscar but the only 100% was to know for sure is to watch them lay eggs. 2 oscars in a 75g will require loads of water change but it is possible. Can you get a bigger tank?

Couple of nice oscars you have there