My tank is very bland with just a filter air stone and one fish in it. i think my oscar is bored because he has nothing to swim around like plants rocks etc. what should i put in the tank to make him happy

this is something I have been thinking about a lot lately. Whereas I don't believe fish have the brain power to actually possesses the emotion that causes boredom, I do however think that fish do better in a large tank that is setup to resemble something like where they would live. The reason I say this is I have got a 300 gallon tank, this measure 8' x 2.5' x 2.5'. I have another tank which is 6' x 2' x 2'. The 300 gallon tank contains two Oscars and a few other fish. The 6 feet tank contains 4 Oscars . Obviously I won't be keeping four, I am trying to find a pair. anyway, six tank hasn't got the decor but the big one has, the fish don't act the same, they tend to sit around doing nothing a lot of the time whereas in the big tank, the fish are always exploring, swimming around the wood and rock.

I really am starting to think along the lines that even 1 Oscar needs more than 75 gallons to itself. These fish do not deserve to be put in small tanks. I think we need to give them an environment that somehow resembles where they come from. It doesn't mean brightly tanks, more along the lines of the subdued lighting with lots hiding places.

in my tank i have rocks, wood, and plants and my os seem to swim around a lot like ofl said.

i notice an increase in exploration after transfering them into a larger tank with more decorations.

im my jack demsepy tank i took a cinder block and broke it in half and siliconed rocks and plastic plants to it. they like the cave i made alot. and it looks nice. i also have a lot of plastic plants on the side of the tank with my os. they swim around it but mainly stay in the middle where its open. they also like those big rocks with holes in them. they swim in and out of them all the time

another idea is to break flat rocks, i used marble slabs, and build 3 pilars. then put a flat rock over like slate and make a house sorta thing.

My Red oscar likes to attack the plastic plants in his tank and usually ends up breaking a piece of the plant off. The piece of plant usually floats to the top and lately he likes to stay right under the floating piece. I didn't think of putting floating plants in my tank, but my oscar loves to hide under it and will wait to be fed. A few days ago I got a big plant that I planted under the gravel and extends 36 inches so most of it hangs over the top. My oscar loves to swims under and through this plant and he is much more active lately.

Can anyone recommend any specific plants, everything I have put in so far has been torn to shreds in a matter of days. Don't know what I have tried just whatever they sell at Pets at Home but nothing seems to last.

Thanks