i have a 75 gallon tank with one tiger oscar in it. it is running a filter for a 150 gallon so im not worried about nitrates or ammonia. the oscar is about 4 years old and 10 inches long. there were previously 2 bala sharks in the tank, but the oscar killed them both as he out grew them. is there any other fish i can add to the tank that he oscar wont kill or them kill the oscar? i live near an exotic fish store that can order pretty much any kind of fish in any size for me so pleae let me know what i can do. i love my oscar fish and i only want the best for it.

If the Oscar has a history of being aggressive towards its tank mates then you could have problems with any fish. You haven't really got much leeway were 75 gallon tank, there's not much more that you could add. You could try adding something like a blue acara and see if that is okay. They only get to about 8 inches at the most and are semi-aggressive themselves so should be okay with an Oscar. However, I wouldn't risk putting in a juvenile.

Your Oscar will be perfectly happy in that 75 all by himself. But if you want some more activity in the tank with him, Silver Dollars are standard Oscar tank mates.

probe1957 wrote:


how many silver dollars should i add?

stain4470 wrote:



I wouldn't add silver dollars. They are good dither fish for the oscar yes, but in larger tanks.

They are schooling fish and usually require groups of about three and up. They can grow anywhere from 5-7 inches (or bigger frequently) and in a 75 that would be way too much. Schooling fish for a 75 would have to be much smaller, to the point that they would become a quick meal for the oscar.

johnnyphoenix wrote:


This is where i disagree with Johnny. SD's are relatively small fish when compared to a full grown oscar. You will be able to keep 3 or 4 SD's in a 75g with an oscar but you have to be prepared for lots of water changes.

The thing you have to think about is that your oscar seems to be aggresive, will your oscar accept more fish in the tank or will it kill them too

Its up to you to decide if you think your oscar will be ok with SD's. Personally i would just keep the oscar on his own

its all personal preference and what your o wants
i was lucky with putting in another O to my tank
but he was bigger then my origanial O and he came from a
non aggressive tank =] hope yu sort summit out =]

maybe you could try a large firemouth

or maybe a small size pleco like a bushy nose?

i already do a 25% water change twice weekly, and my oscar is very healthy and active.i dont think i would need to do any more water changes then i already do to get 3 SDs. am i correct ant
could get 3 SDs around 6 inchs?

as i said, test your water weekly and if your nitrates are above 40 then you will need to do more or bigger water changes. If your nitrates are above 40 regularly then your fish may get ill.

Interestingly a 50% water change once a week is better then 2 25% water changes