One of my 2 oscars has been spitting rocks against the glass and "rearranging" the tank. What does this mean?

Firstly id like to welcome you to oscarfishlover.com hope you enjoy your stay with us and if theres anything we can help you with please do not hessitate to ask any questions as there is many experienced fish keepers here that are sure to help you.
could you please fasten yr seatbelt and get ready for take off.

Spitting rocks against the glass could be many things depending on yr tank size,water quality ect.

it is very common for oscars to rearrange their tanks as they are very territorial and like to adjust things the way they feel is right despite what their owner think.

if you have a male and female in your tank this could be one of the many signs that they are ready to start breeding.

could you please tell us a bit more on the age,size of yr fish and what size tank they are in so we could understand a bit beter what is happening in yr tank.
Regards

Thanks for the welcome! The tank size is 55gal, which I've recently found out is too small for 2 Oscars. The largest is about 9 inches and the smaller of the two is about 7 inches. I do water changes 1-2 times a week right now just to make sure the water is clean. I don't know enough to make sure all the levels are ideal but I did take a sample into my LFS about 2 weeks ago and they said everything is good. The tank is due for a water change now but the larger of the two has been creating big piles of rock and if they're getting ready to breed I didn't want to disturb anything. Should I clean out the rocks even though he's done all this hard work? I would like to have them as a breeding pair if they're male and female so as much info as possible would be very helpful. They seem happy except if I accidentally disturb them while they're resting.

water changes generally initiate swaning if u hv a look here on the left side of the webpage u will find info on breeding and pairing oscars.

good luck with that