Hi Peter
It depends on which dwarf snakeheads?
I used a keepa few and bred Orientalis
My orientalis I kept in a 24x12x12 which would probably be frowned upon but they did well in there. Assams and Bleheris again I kept in a 36x12x12
dwarf channa are amazing fish and would be the first fish I turn to onceI get a house that can have more tanks again
Simon