I'd put the tv on a console to the left of the fireplace and the fish tank to the right of the fireplace on a matching/coordinating console. Place a piece of art above the tank the size/shape of the TV. Place your couch on the big blank wall. That way you'll keep the symmetry going along the flanking windows.

Forget about art above the tank. That would not work. Just place the tank on a console. Maybe a nice piece of art above the fireplace and above the couch.

Perhaps show the other rooms? This does not sound promising, and an entry door opening directly into a bulky reclining sofa does not sound or look great, though Beverly's attempt is about the only possibility.

I was going to say what beverly and enajas said. But you may not want the fish tank close to the windows if you get direct sun there. The TV to the left of the fireplace for sure. The fishtank TBD. I dont know what the other choices are. Do you have a floorplan of the whole main floor?

I updated the post with photos of the rest of the main floor. its a one level with 3 beds and 2 full baths. 2 of the bedrooms will be offices.

I would begin by using that whole FP wall for TV, fish tank some storage and a bit of display. You might be able to hack Ikea Besta to do this or a custom unit the fish tank is the puzzle . How big is the tank what kind of fish and what is required for it to function dailiy? Pics of the tank in the home you are in now would be ahuge help. The realtor photos are never helpful we need a to scale floor plan and mor einfo for sure about the fish tank We had a large salt water tank and the smell was just not pleasant so we moved it into a different space in the house .

Its a forty gallon tank. Doesnt need much the filter hangs on the back and its got a glass lid. All it needs is access to an outlet and close to some sort of water source for water changed - we have a special hose that connects to a sink and we can extend that however long we need to. we dont have a floor plan yet but hope to have it soon.

You could add a palm to keep the sun from shining on the aquarium.