In college I managed a betta.
By grad school we had 2 guinea pigs with periodic young we sold for more food; we had a salamander tank (survivors of limb regen experiments at Hopkins); we had a guppy tank; we had angelfish; we had a piranha tank (got him for fifty cents, as a goner, pinned overnight under a fallen decoration: he survived and became a beautiful fish); and I had two largish seahorses which were doing fine until our downstairs neighbor threw a party with so much cigarette smoke coming under our doors it made a pall on our ceiling and did in the sea-horses.
The rest, however survived.