We've had an Oscar fish and a plecostomus for about three months now and they get along pretty alright. Sometimes the Oscar fish nips at the pleco and the pleco bites back but nothing too serious and they mind each other's business for the most part. Yesterday we bought a 7 inch arowana and the Oscar fish seemed intimidated at first but early this morning we woke up to find that it had attacked and killed the arowana. I've read about Oscar fish behavior completely changing once it manages to kill a tank mate and I'm concerned that mine might go down the same path. Is there anything I should be looking out for and what should I do if my Oscar fish experiences any changes? Thanks!
Need help with my Oscar fish
- Thread starter WDBono
- Start date
The oscar now sees the entire tank as its territory, and it will probably try to kill anything else you add.
What size is the tank?
An oscar can easily see an entire 6 ft tank as its territory.
What size is the tank?
An oscar can easily see an entire 6 ft tank as its territory.
Update: My Oscar fish is now twitching and swimming erratically which causes him to bump into other aquarium fixtures. Concerned that he might go for our pleco. Anything to do to fix this?
I didn’t physically see it happen but when the arowana was introduced sometimes the Oscar would like nip or bite it at before retreating to the bottom of the tank. I was only told that the arowana had gotten attacked and now my Oscar fish is exhibiting strange behavior that it didn’t before like thrashing about and staying in one place in the aquarium where normally it would just swim around the whole tank. Water was tested when the arowana arrived and everything checked out. It didn’t really have much of an appetite (but my last arowana was like that too, not eating for a few days before getting used to everything) so everything seems to point out that the Oscar killed the arowana. If there’s any other causes that you think happened please let me know!
What are the water parameters? The twitching doesn't sound right.
It does sound like the Oscar didn't take a liking to someone moving in to his house. I think in most cases once an Oscar has made it his territory you're going to find it extremely difficult to introduce any else without absolute mayhem.
It does sound like the Oscar didn't take a liking to someone moving in to his house. I think in most cases once an Oscar has made it his territory you're going to find it extremely difficult to introduce any else without absolute mayhem.
Did you Quarantine the new Arowana before adding it to the oscar tank?
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Nitrate, nitrite, and ammonia is all 0 and the pH is 6.8. We’re thinking about doing a water change on the weekend so hopefully that helps!