I'm going to disregard fish tank size
Is there a reason for disregarding the size?
Engineers are working on ways to make fish tanks larger.
It's expected that people take care of their pets. Therefore, you should always get the correct sized fish tank for fish.
I've learned that smaller tanks allow you to feed your fish more, so they like it.
Even if you can feed them more it would be better to give them enough space to swim. How would you like it if you had to live in a tiny world with no way to escape?