Itsits normal for them to gulp air, knifefish have a kind of air breathing lung organ that lets them take in atmospheric air so survive in low quality water. Not saying your water is bad, its just normal behavioral instincts for them.
ok that is good to know....thanks...
one more question...heh...I want to buy black ghost knife...is it gonna be ok in 80g aquarium?
now he is around 10cm long and is it true that the black ghost are blind?
does any of you guys have black ghost...?