I had a small reef tank for a while. I had a lot of different corals, a tiny anemone, various invertebrates, and a yasha goby. After several months, most of my corals suddenly died for no discernible reason. I took the tank down a while after that and switched to planted betta tanks.
Current bettas: ♂Opalo, ♂Granite, ♂Alpha-Betta, ♂Eclipse, ♂Lucky, ♂Honor, ♀Virtue, ♀Innocence, ♀Garnet, ♀Chroma, ♀Tethys, ♀Amaryllis, ♀Goldeen
Tanks: 3g betta NPT, 20g NPT community, 10g 3-way divided, 10g NPT sorority, 5g divided betta tank