Got two oscars. Each about eight inches, and one red tail shark about 4 inches in a 120 gal 4x2x2. If I still have room I would like some kind of catfish or algae eater. Something small. Maybe 4-6 inches full grown that would help keep tank clean. Any suggestions?

IMO, You are maxed out!! Don't add anymore or you will have to do a lot more water changes!!!

Hmm I think you could get something else in there (my tank is a LOT more stocked) - although I am upgrading to my 6' tonight.

It is true that you have to do a LOT more water changes though - atm I am doing 50% changes every two days to keep things under control until I upgrade.

My stock:

2 x Oscars
1 x Blue Acara
1 x Jack Dempsey
1 x Electric Yellow
1 x Electric Blue
1 X Pleco
1 x Chinese Algae Eater
1 x Black Ghost knife
2 x Green Severums
1 x Piscus Catfish

Yes I know large bioload and overcrowding ... my sump setup does help this somewhat though (extra 150 litres of water), but I will need to get risd of a few things when they grow a bit more

As for a fish to clean - would recommend piscus catfish, black ghost knife (awesome looking fish!) or chinese algae eater as great "clean up" fish

Goob_Scooper wrote:

Problem is sometimes things come up unexpected and if your tank needs so much work to keep parameters in check, trouble is around the corner...
I like my setups to have overcapacity in filtration and watervolume, to be on the safe side, if for any reason i cannot do maintenance for some days!

I was thinking some kind of bottom feeder might eat some of the oscar crap and that would reduce bioload a little. I realize hes gonna crap too, but wouldnt it be less than the crap hes eating? Am I completely wrong?

youre bioload is build put by the poo of your fish.
Adding a cafish will probably clean up a lot of mess but he'll upgade your bioload by pooping out a lot...

All fish produce waste, there is no 'free' fish. Adding another fish will add waste and will increase the frequency of water and filter changes

Having said that i think you have enough room for a plec and maybe a small tank mate. Lots of people on here dont like plecs for various reasons but i like them. They poo lots and will increase the need for water changes but they clean the glass and rocks for you. I hardly ever have to clean my glass, I feed him algae wafers once a week. I think they look great too. You will be looking at a 50% water change everyweek without fail if you add a plec

im not trying to get off topic or anything.... but in my experience snails work A HELL OF ALOT BETTER than plecos for cleaning up my tank, and they cant bite murderous holes in my oscar in the middle of the night.