Angelfish.
 

I would like to own an angelfish, but I only have a 4-gallon tank.
can angelfish survive in a tank this size?

No. There are no angelfish that will stay remotely small enough for a tank that size. The myth that fish only grow as large as the tank is just that, a myth. An angelfish will quickly outgrow the tank.

ooh, ok. thanks!

what kind of fish would do well in my 4-gal tank?

Well, a betta would certainly fare well. If you're feeling ambitious, and up for a sensitive fish which requires top notch care, a dwarf puffer is a very fun fish to keep. There are many killifish which would fit in your tank. They can be tricky to find since they aren't really bred commercially, but many of them are said to rival the colors and beauty of a saltwater reef fish, which I would agree with.

dwarf puffers,oodles of personality for a little dude.
can be very agressive,non comunity,needs plenty of decor in the tank
to break eye line if there is more than one.

well I had 2 bettas for over a year and a half.
and they passed away this summer.

and I loved my litte bettas. but I kinda want a different fish.

The dwarf puffers are very neat fish. I have some myself, and I just helped my brother set up a 10 gallon tank with three of them.

They're the cutest little fish in the world with very curious behavior.

They *do* require some special care, as they're more sensitive than most fish to poor water conditions and they need special foods (i.e. live snails). You should be able to find pond snails at any LFS though, and set up a breeding colony in a 1 gallon container.