hi mate , some things you need to decide first , what is available in your area , snakeheads are not freely available in every shop and some place they are hard to find . on the poss side there is probably a snakehead for you no matter what size tank you have got (within reason) , what is the size of aquarium you would be happy with and realisticly be able to house , then we can give you some further guidence and ask you some more questions
cheers col