I have a twenty gallon and a five and a half gallon. Both are heavily planted tanks with a bunch of filtration. The tanks are heavily stocked with small freshwater fish and inverts.
Get the biggest tank you can, test water parameters and change water. If you get more fish, get more plants and filtration.
Platy, Betta - Male, Neon Tetra, Glolite Tetra, Dwarf Gourami, Endler Livebearer, Cherry Barb, White Cloud Minnow, Corydora Catfish, Pygmy Corydora Catfish, Bristlenose Pleco, Kuhli Loach, Ottocinclus, Snails, Vampire Shrimp, Pompom Crab, Thai Micro Crabs, CPO Crayfish, Bamboo Shrimp, Amano Shrimp, Red Cherry Shrimp
Java moss, anubias, amazon sword, luwigia repens, watersprite, salvinia, duckweed, dwarf water lettuce, moss balls, dwarf hairgrass, java fern, hornwort