NOT a wise choice although I have my 6.5 inch dwarf Gachua with my 13 inch Gar and they do fine in my 120 lots of hiding places tho and on top of the it is a TEMPORARY ARRANGEMENT but with any chance Gar goes for her every time.... she too quick and smart lol she Deaks him out lol
Wolf are to unpredictable and dwarf would be fine in a 30 by its self. I have had mine with two clown loaches and and small spicices of pleco.never a problem. But as all the guys mentioned hey are best kept alone or in small groups........ most snakeheads cant stand each other.
I am a bit surprised though nobody has asked what species your thinking about before giving advice.
Many dwarf species are subtropical which eliminates many possible tank-mates right away. Some "dwarf" species are very aggressive, others are far more tolerant of tank mates so really although the general rule of thumb is to keep snake heads solo or species only there are a few exceptions.
As for how many per tank it also depends greatly on what species .
Totally never thought to ask but as you said DC depending on the species. Gachua seem to not mind tank mates as long as they stay away like in my case loaches worked and and orange seam pleco but they rarely crossed paths. The loaches on the other hand were always near her but she could care less. So what which were you thinking man ?