it does have one, it's 7mm acryclic!Oh I just noticed something: Your tank has no lid? I hope it's just a visual effect, because that'd be the doom of your channas, eventually!
well it can be after their poopIt looks like old, un-eaten food to me, just scoop it out! That's one sign you are over feeding. If they were that hungry, they would sniff out the majority of the bits left after feeding.
I've never had fungus grow on poop, and I've had a tank not have a drop of water removed or added to it for over a year. My aurantis had the most clear water I'd ever seen, and it had not been water changed at all.well it can be after their poop