Its not feasible, it is certainly possible I've seen it done before and I attempted it myself. That tank turned out a total disaster it was properly cycled, but nothing I could do would "balance" it and the only thing happy in there was the algae. The amount of maintenance my 2.5gal tank required was the same as my 20gal high tech planted. Eventually I turned it into a terrarium and currently it just grows plants.
The betta, endlers, or adf's are all good options and the most common. Bettas are always suggested first because they are the best suited(they'er indestructable). It is almost impossible IMO to have such a small tank stay stable, the larger the tank the more stable it generally is. I'm not talking about the cycle, but other water parameters GH, KH, PH and temp to mention a few, tend to fluctuate a great deal in micro tanks. Live plants are almost neccasary IMO as they add to the stability.
Fish <;((((< that are suited for small tanks, Micro rasboras. You won't find these in shops. You can get them online easily, but then you have shipping charges. $30 is usually what it costs, sometimes $15 if they will shipp priority. Considering you only want 4 fish it is not feasible to order them this way. But below is a list of fish that can be cept in small tanks. Rasboras are more peaceful towards each other than tetras and they don't activetly swim around, they usually hang around a general area. I keep B. Brigittae.
Boraras micros - .5-.75 inches max
Boraras merah - .8 inches max Boraras maculatus
- 1 inch max Boraras brigittae
- 1 inch max