Yeah, people who rent apartments don't start up fish rooms. Home owners start and maintain fish rooms. Adults with decades of experience start and maintain fish rooms (I'm sure there's some younger folks out there with fish rooms too). The first time your landlord sees more than a few tanks in your apartment he/she will consult your lease agreement and point out the breach.
You may want to reevaluate your plan. You're young and have plenty of time to have fish rooms in the future...
My cousins friend has a fish room. Idk if he rents or what, but I am pretty sure it is a house house not an apartment.
Sit down with your land lord and your lease agreement. He may not like the tanks you have now. I also dont think he would like the "junk room", so make sure you clean the entire apartment before meeting with him. My room can become a pig pen in 15min of me set on doing something specific. But when I want to relax, it is so nice to have it clean. Like I said before, turn on the music and get cleaning. Your landlord may normally not allow it, but if you have the apartment clean and you are very respectful to him, he may allow something. But I doubt an entire fish room will be allowed. That is a big liability for both of you.
I just went through that whole thing calling the landlord a man, when it could be a woman. Oops.