I have four 7" Oscars in a 125 gallon tank, the original aim was to get at least one breeding pair from them, then move the other two to another tank. What signs should I look for that a pair is forming up, and what should I do when this happens? I want to keep the tank as a display as much as possible, so trying to avoid the egg-crate seperator.
they will start to build nesting pits ,and become very territorial if you thank they are going to spawn then I would put a large flower pot in the tank
I have always had good results by feeding the prospective breeder Oscars all the large nightcrawlers that can eat coupled with large frequent water changes.
I almost always get a spawn, even from a group of six unrelated fish thrown together within a month of initiating this regime. I have never bothered with dividers. They must have some chance to practice their ritual battles. That your fish are digging pits hints that they only need some attention described above and you should have results shortly.
Females "pairs" are the exception and not the rule. I personally have never had that happen.
If you have a female pair, eggs will always rot and die. If you build a large cave with stacked rocks or a large ceramic pot. May work. Give them mulitple places to spawn.