My tiger oscar has been acting strange the last few days. He will rub or head butt the side of the tank where his reflection is. Also he used to greet me at feeding time and swim around the tank when the light was on and now he sulks behind plants at feeding time and when the light is on and wont eat until I switch the light off.
His food was recently changed and he wouldn't eat the new food for 2 days which resulted in messing up my water conditions but they are now back to normal.
He also recently had his tank mate die of old age.
Maybe get the same species of tank mate that's the same size, and switch back too the old ffood
His tank mate was a lyre tail molly he was with since a very young age. I got them when I had no clue about fish and now that I know that oscars are aggressive I dont plan to stick anymore mollies in with him. Im honestly surprised he never attacked the one he was with. Instead it was like his pet as he got bigger.
And I cant go back to his old food because the pet store I go to quit selling it for some reason.
What size aquarium?
Can you test for ammonia, nitrites and nitrates?
55 gal tank
nitrates and nitrites in the ideal range.
I use dip strips so I cant give a exact number for them.
As far as testing goes I would really recommend the liquid test kit (api master). It will give a clearer reading even though the color charts can be a bit ambiguous if the levels are very high. There shouldn't be an ideal range for nitrites. If your bacteria levels are optimal than nitrites should be zero.
I'm fighting the fight against nitrites myself. I've got some progress, but still too toxic. My Silver dollars tend to act a little weird at times too. After checking the levels I see that it's time for a water change. Afterwards everybody seems to calm down a bit.
Is he rubbing on any objects in the tank?
DO you notice any bubbles hanging on/off of him? Like he would be losing his slime coat?
What kind of food are you feeding? Try tempting him with something like frozen bloodworms, as a treat.