Any type....just get the single fish a bowl.
Happy Aquarium last forever. If you do want to get rid of your fish, just sell them. The best fish to sell are the adult fish.
Clap your hands on it. That's the simplest answer i can give.
Bettas, Siamese Fighting Fish. I may have missed some, but if your talking about small fish, I hve most of them.P.S. NEVER and i repeat NEVER put two male Betta together!!!!!
Most any aggressive larger fish will kill it.