Hi Julien,
nice tank, but a littkle bit more surface plants would be really appreciated by ypur channa.
By the way, these are NOT Channa bleheri. You have a yet scientifically not described species called Channa sp. "Assam", or "lal cheng".
Sadly they are often sold as bleheri or blue bleheri, but they arent bleheri at all.
bleheri are surface breeders/nestbulders, and sp. Assam are mouthbreeders.
But both species are subtropical, and should not be kept at tropical temperatures all the time.
Cheers