snakeheads don't need that much current, some of my channa tanks are stagnant. The fact that they can breathe air and are very tolerant to dirty water makes them pretty indifferent to water flow. Actually, most channa aren't great swimmers and prefer lower current so I would advise a smaller filter with a lower turnover rate but it doesnt really matter. If you have enough plants and your tank is able to cycle itself relatively efficiently such that you dont constantly need to do WC it will be fine
