So the Oscar is now seperate from the Afs.? And how are the Afs. acting together in a 30??
I agree with the person who said the Oscar is just reaching sexual maturity. He/she will never get that its the only Oscar around. My Frontosa used to make nests all the time when he came of age. I always felt bad because I couldn't help but think that he was thinking any minute another Frontosa would just HAVE to come swimming by because he couldn't be the only one in the world
Maybe you can work on your mom a little by pointing out that a 75 would still be only four feet long, just like the 55 and that you could most likely (depending on what you have I guess) use the same equipment you are using now. And start checking the want ads for a cheap one then point out that it wouldn't cost THAT much to upgrade.
I've found that reef internet sites like Reef Central have people selling set ups or just tanks all the time and the tanks are always real cheap (usually way more so than freshwater sites). Pretty much $1 per gallon or maybe $100 for a 75 with stand. Check it out.