The one that lays eggs is the female and the one that fertilizes them is the male
Only the Oscars know.
Actually the best method I've found is to put a known sex non-Oscar Cichlid in with them. (Female Oscars will behave aggressively to male OR female Cichlids in the experiences with my 5). I put a male Texas in with my Veiltail and I could tell by his reaction (he was in love) that the Veiltail was a female, that Texas hated all male Cichlids. My male Green Terror will also fight with all males but he runs from female Cichlids. That's my redneck way of figuring out genders lol Other than venting them there's no 100% way to tell.
Oops, I meant to tell you....the beneficial bacteria isn't in the water. It's in the filter media/sponges and on the decorations & gravel, etc. So you might want to keep your test kit handy if your filters weren't cycled and you only used pond water. You can't cycle a tank using just water from a cycled tank (or pond), you need the filter material. Maybe you did that, I wasn't sure by your post.
i stole 50 or so bio balls out of my outside ponds biofilters. yes i know that. and i didnt take them out of the water, i just scooped a 5 gal bucket in and pulled them out. then i put about 500 gallons of water and a couple plants out of the pond. i think i should be good.