[OLS]

I can tell you a few things about fresh water tanks, best thing they ever invented was that "tank cleaner" tube you get a siphon
running in that thing, and jam that wide end into the gravel and shake it around a bit, bits of $hi+ and old food come roaring up
through the tube while the gravel can't make that 8-9 inch trip up to the hose part. The day I learned how to use that tool was
a GREAT day. By the time you have a 5 gallon bucket full of water, most of the debris has settled to the bottom of the bucket,
making cleaning the gravel a snap. And you HAVE to do that with Oscars. I think the 'scars' on your oscar's head is basically HLLE,
"head and Lateral Line Erosion" and it happens to stressed fish that live with stray tank voltage, poor diet. Don't feed them all
feeders even if it's fun. Give em shrimp pellets and a little cooked chicken, vary up the diet more. They like roaches and crickets
too. You might want to get one of those voltage anodes to put in your tank, they are cheap and effective, and can also help save
YOUR life. They are no Ground Fault Circuit Interruptor, but they take care of stray voltage very well. Makes your fish less jittery
and nervous and agitated, good things with Oscars.

I am surprised to see goldfish and oscars iving together. Were they feeders who managed to evade capture and got too large
to mess with? Back in the USAF, everybody in the dorm had a fish tank it seemed, a really popular diversion back in the good
old Reagan days when we were not fighting everybody on the planet. It always seemed to be African Cichlids or Oscars.
I know that last fish pic...Kribensis, lol.