Can my fish tank support an Oscar?

Keep in mind that oscars can reach a healthy foot and a half in length, and at that size, will have a lot of trouble maneuvering in a 12" wide tank. Fully grown oscars in a 55 gallon tanks never reach full size, and typically live an abbreviated life.

An Oscar really needs a minimum of a 75 or 80 gallon tank.

Maybe you saw a video of an Oscar in a 55-gallon tank, but you don't know how long it was in there. Maybe only a few minutes.

A clown loach gets to be a foot long, and should be kept in schools, so about 125 gallons is the minimum for clown loaches.

There is no tank that would fit in most houses yet is big enough for an iridescent shark. This fish grows to be about five or six feet long and over 100 pounds.

So I guess my "tip" is to get a bigger tank, and lose the iridescent shark somehow.

"Any tips on raising oscars?"

Yeah, get a bigger tank ;-)

Yes you could keep an Oscar in a 55gal, but it will probably never reach it full size, and you will need very good filtering and lots of water changes. A large pleco is probably going to push you over the limit.

Right now I have a 12" pleco and a 4" Oscar in my 58gal, but I know they will outgrow it, and soon, so I have an 82gal to move them to. That should do them for life.

Adult Oscars are BIG messy fish, and so are Plecos. 55gal seems like a big tank, untill you see it with 12" long fish in it. They can barely turn around, and a long swim is a couple of body lengths.

Ian

A full grown pleco needs 120 gallons if its a common pleco. Either your pleco is a dwarf species or not fully grown. A common pleco can easily reach 18" in size.

Anyway, 55 gallons is just enough for 1 baby Oscar if it's empty. Adult Oscars needs 75-90 gallons each.