An oscar needs alot more than a 23 gallon tank, IMO a standard 75 is minimum for one. Just curious, how big did your neighbours jack dempsey grow to in that tank?[/QUOTE
It is 4 years old and 9 inches long.
Carl (my neighbour) feeds it a high protien diet (and even worms from outside sometimes!).
He does a water change of 25% twice per week.
The tank has good filtration.
The fish is quite attractive...very nice colouring.
It is very hand tame also. He will stick his hand in the tank and the fish is very interactive. The fish doesnt mind if Carl touches it, it doesnt get startled. The only thing is...it tends to be aggressive toward other people. The fish will attack my hand if I place it in the tank....yet Carl can rub him. I guess it's used to its owner. lol...then again, I think the fish ownes Carl. He babies that fish so much...
Although tank size is important...I find some people to be overly obsessed with it. What is mostly important is maintain good water quality and diet. If you think tank size is the most important role in how large a fish will grow.....try a lil experiment: Put a baby Jack Dempsy in a 100 gallon tank by itself and make sure the water quality and diet you give it isn't good. You'll notice the fish won't grow much...despite all the room you've provided it.
One of the local fish stores actually has a baby oscar, by itself, in a 50 gallon, for display. The tank isn't well kept at all...and they can't understand why the fish isn't growing, even after months!
(not actually recommending you do this to a fish, just proving a point)