I have an aquarium on my desk. Within it are two shubunkin goldfish, whom I love dearly. I have had numerous aquariums throughout my life, with various types of creatures; for years and years I had a tank of hissing cockroaches and I even wrote a writeup about them. It was only through having these aquariums through the years that I have become aware of what I would consider mistakes, mistakes that caused me to enjoy my pets less, wasted time and money, and aren't at all easy to identify or prevent. I think there are definite choices a person can make in order to enjoy the aquarium more. I shall attempt to share my experience and advice here -- I do want to assert, I don't claim that my experience is universal or absolute; this is just what works for me!
Mine is on my desk, between my computer and the door; I spend a ton of time looking at it, even if I'm not trying to. I get to enjoy the tank a lot because of this. I get to interact with my pets. I see my pets, they see me, we think about each other. My fish try to swim through the glass to get to me, they like to watch me as I type on my computer. I have made the mistake of placing aquariums in low-activity areas; on my dresser, in my corner window, etc. In some of these instances, I forgot about the creature, and it died. This was what happened with my cockroaches; they kept breeding such that I had to move them into a big tank. The big tank was best situated in a corner window that I never looked at. Eventually I forgot about them and they all died. This also happened with an old aquarium I had like a decade ago. The tank was on my dresser. It looked great on the dresser, but I never looked at it. It was out of the way, and I forgot about the fish. I don't know how it survived, but the water got filled with algae and all this weird white slime. I gave that fish to my mother when I realized I couldn't properly care for it, and the thing lived for years in her kitchen.
Each animal gets a name. Each plant gets a name. Even the decorations, if they look like animals, give them names. To name a thing is to give it real estate in your psyche. If you can't tell them apart (as was the case for my cockroaches), try to observe them and see if you can tell them apart by their personality. That sometimes works. Think long and hard on the name; I have found that the right name greatly strengthens my emotional attachment to the thing being named. I could choose another name, but then it wouldn't be as special. When you find the right name, you will know, deep in your heart. My fish are Tuesday and Banquo, and the pothos plant hanging out of the tank was named Samwell before they ate all the roots. I want to attempt to introduce some marimo moss balls to throw in the thing to give it another splash of life; if I do get a few of those, they will all be named. But, of course, they might eat it. Goldfish eat things.
You don't have to roleplay in your head that they will understand you (in fact I do not recommend doing that) -- just talk to them when you interact with them. Talk to them when you notice them. When I look at my fish I say "Hello fishies! Fishy fishy fishy! How are you doing today Tuesday? Chewsday, innit. You're just a little guy, aren't you? Are you guys hungry? Do you need foodstuff?" Seriously, these little interactions GREATLY increase my emotional investment.
Spruce the tank up, spend a few extra bucks on decorations that make it nicer to look at. Maybe you want a lush cave sort of look, or perhaps a colorful neon sort of look. Or beige rocks and driftwood. There's so many options! You don't have to do this all at once; a plant here, a rock here, the decor isn't going anywhere. Full transparency though, I will confess that I have yet to do this with my current aquarium besidse a few plastic plants -- this is mainly because I want to decorate it with NATURE, but the fish eat everything I try and put in. It's so frustrating because I would feed them plentifully to try and prevent this. Grrrrr. I am thinking the next step for me would be to add maybe a PLASTIC object of some kind, but I am undecided on what exactly. Maybe some kind of castle bastion.
I am sharing because it is something I have noticed is a requirement for myself specifically. I originally wanted to do a guppy tank with a school of guppies, but they only live 2-3 years, and I hate hate hate losing fish. It's the worst feeling, it ruins my week. I got goldfish because a goldfish will live fifteen years on average. I wanted something I could grow fond of. Admittedly guppies are prettier, as are bettas, but bettas too only live one to two years. Ugh!!
and finally ... have fun with your aquarium!! It's such a fun hobby. I would love to get into aquascaping someday but... not possible with goldfish. They eat everything. Seriously.