What is the best type pet fish for a small tank

few basics for a small fish tank.

keep atleast 5 ltrs of water per fish. so if u have a 20 ltr tank, then dont keep more than 4 fishes

put fishes that not make the water dirty, eg, gold fishes eat a lot, so u have to feed a lot, adn the residue remains in water, they also eat and spit out food, adding to sedimented food particles, they also * a lot,,

all these factors adds to decomposition of stuff and addition of ammonia in the water.

this leads to unhealthy water and sick fishes affecting the size, growth and color of fishes.

i recommend putting fishes like angles,,, they are very disciplined and will not contaminate water. more over they react to ur presence and u will enjoy the pet. more over their majestic movement helps cool down ur stress levels, and helps phychological development of kids as well.

mind you, maintain the natural cycle in the tank, keep less fishes and adequate plants and lighting,, the ammonia generated by the decomposition of food waste and fish waste is absorbed by natural plants and algae,, to keep the plants healthy, and functional, have sufficient light.

this will ensure a healthy natural fish tank, all u need is an air supply to dissolve oxygen in water, and u will nto even require a water filter,

community tank fishes go together, angles, goldfished, molly, guppi, neon, tetras, sword tales, etc,

dont put guramis and fighters in community tanks,

small sharks are also harmless but ur tank is small u said,