Hey,
There are a lot of Dwarf snake head species coming onto the market, last year two more were found in Myanmar (Pulchra and Ornatipinnis) both gorgeous species, but they come from sub tropical climate in fast moving water so wouldn't make a good tank mate for an Arowana. I wouldn't suggest Bleheri as a tank mate either, they stay far too small, but as for growing slow and only maxing out at 8 inches I would have to disagree, if fed a wide range of food and given a large tank with a lot of circulation they grow like weeds. Also some of my larger Bleheri are pushing 10", and very very chunky. They are very quiet, but come from slightly cooler water than asian arowana and require a lot of vegetation to be happy.
In order to breed Channa the best tips I can give is be aware of the species. Species range from needed a higher ph, cool water, and strong current to be happy. Although other species like it a bit warmer with a neutral to lower ph. But for Bleheri, slight current, sandy bottom, with drift wood and rock work, and lots and lots of tall bushy plants. Feed a lot, cool to about 22 degrees celsius for about 4 months, feeding does not have to stop but slow down, make sure the water stay very clean and water levels stay high during this period. Nearing the end of the 4th month begin raising the water temperature, over a 6-8 week period, once at 30 degrees celsius, allow water level to go down and water to get a little scummy. It will usually trigger breeding. It's no science, just the way I went at it and it worked. I have a good ratio of 4 females and two males.
Better species to mix with arowana would be aurantimaculata or pluerophthalma, they both get about 16", and even though they are a tad more aggressive than bleheri, if the right one is found they would probably work out great.
Good Luck,
Justin Morash