Hey guys new user and oscar keeper to be here!
I'm 19, i have been keeping aquariums since i was 7.
Boy, that means my 55 gal is 9 years old.
I got my 55 gallon when i was 10 and kept a community tank for 6 years and for the last 4 years ive had African chichlids!
Well Im moving on in life now and ive really grown out of the whole community tank thing, it was great, but its just too much effort and time right now. Plus my malawais are getting very aggressive and I cant introduce any new fish without majo drama and I am very annoyed at them.
So basically I want to ship out the old chichlids and introduce a new single oscar (a fish which will grow large and will have CHARACTER.)
My problem is, what to do with the old fish, I would like to find a buyer and I know pet stores will just rip me off. (Ill be so sad to see my clown loaches go

)
i was just wondering about filtration, is a single submersable filter ok? it does the liters per hour nessessary for a 55gallon.
Also, is the oscar fine by themself? I plan to give it lots of love and attention

.
Thanks for your help.
PS. my other more.. aethetic concern is scratches, being a 9 ear old tank (been resealed a few weeks ago) ithas a few scrathes that are noticible if you are about.. an inch away form the glass (im very picky

) is there any way to reomove them?