For me a 100 gallon planted tank with sand filter one of those machines that add CO2 all sorts of plants driftwood lava rock hiding places natural decorations and five assassin snails and a male Betta and a 100 gallon planted tank with a guppy colony.
Is this an unattainable dream or a realistic dream? I've got planned setups in the future, and then I've got crazy dreams that I would need to win the lottery to accomplish.
My realistic dream is a 150 gal discus biotope with schools of cardinal tetra, rummynose tetra, and black neon tetra. It will probably cost a few thousand dollars to set up. A 125 gal SE Asian river biotope with denison's barb and some other cyprinids would also be amazing. But again, another couple of thousands of dollars.
My completely unrealistic dream is a 50,000 gal sturgeon pond with side-viewing panes. :P Not gonna happen unless I hit it big.
Large community tank (100+) with glass catfish and black neon tetras and...not really sure what else yet, haha. I've always wanted to keep Angels too, although idk if they'd be compatible. Kuhli loches too...
Large tank for rope fish (they're SO cute!) or a tank for any type of snake-looking fish (eels, bichirs, etc.)
A large custom made tank for an arowana (no colour preference)
See: my own personal Marineland
And for saltwater, I've always wanted to own seahorses...
A tank full of piranhas in my secret lair... under a volcano...
I MEAN JUST A NORMAL TANK OF GOLD FISH. Nothing suspicious or evil about that!
No but seriously, if I could have anything fish in the world, I'd want to have a koi pond. I've heard koi are like dogs once they get used to you. In that they learn their names and come when they're called and let you pet them.
But if we're talking about aquatic life in general then I have to say what I really want is a mimic octopus.