It's pretty common for college students to keep fish as pets. They require much less time and attention than cats or dogs. And, if you live in a dorm it may be the only pet you are allowed to have.
Before you get a fish, I need you to know that this,
AND ESPECIALLY THESE
ARE NOT OKAY!
All of the above setups are way too small for the fish inside them. Fish housed in these situations will be incredibly stressed until they die an early death from a preventable disease.
I have also heard people I know flushing their fish at the end of the semester because they cannot bring them home, or are tired of caring for them.
Fish are living animals and owning them requires the same type of attitude as owning a dog or cat. They are not just decorations. They have specific care requirements that you may not be able to afford or handle as a college student.
Regardless of the species, you should not adopt an animal if you are not absolutely sure you can dedicate the time, money, and attention required to keep an animal healthy.
Just because it isn't a dog, doesn't mean you aren't neglecting an animal. Not providing the minimum requirements for an animal's well being is animal cruelty. Killing a fish because you no longer want to take care of it is animal cruelty. It's also extremely fucked up.
If you are looking into adopting a betta, they need to be housed alone in at least a five-gallon tank with a low-flow filter and a heater set at 78 degrees Fahrenheit.
If you want to adopt a goldfish, one fancy goldfish will need at least a ten-gallon tank, and one single tailed goldfish need a 40-gallon tank at the minimum. Obviously the more fish you get the larger the tank should be.
Fish need to be fed every day, and their water needs to be changed and treated weekly. Fish can get sick like any other animal, and they should get proper attention when they are ill. Keeping them in dirty water can increase the chance of them getting sick, and not treating them can cause death.
Before you buy that flashy betta at Walmart, do some research. The more you put into keeping an animal, the more you will get out of it.
Owning fish can be really rewarding, and the happier the fish is the bigger the personality you will see from them. If you can afford the basic requirements of owning fish, and you are willing to dedicate the time to keep them happy and healthy, then do it! Fish can be great for college students to keep, just do it right!