Sponge filter! Personally I think these are the best filters. You're gonna need an air pump to hook it into, but the best part is that you can use multiple sponge filters with an air pump, with more aquariums. It also adds oxygen to the tank because ...
Top Fin® Aquarium Sponge Filter
Air pump! This one is a dream. When I say it is silent, it really is silent. I sleep next to it and there's not even the slightest buzzing sound coming from it. It also is really small in comparison to other models. Highly highly recommend!! ...
✔️aPump Quiet Aquarium Oxygen Air Pump - Silent Adjustable Air Compressor 🐠🐬
Live plants!!! This one's my favourite because you can just attach it to anything (wood, rocks), you don't have to bury the roots (it doesn't have roots). Just glue it to a surface, with proper aquarium safe glue!!!, and leave it do it's own thing. I...
Java Fern "Narrow leaf" For Sale - Medium | Petco
Driftwood. It looks nice in the aquarium, provides good hiding places and it also releases "tannins" which is beneficial to fish.
Imagitarium Aquatic Driftwood, Large | Petco
So so important!!!! No matter what fish you have you need this to cycle the tank (nitrogen cycle). This works so much better than strips because it is accurate.