I don't know if this is the answer for sure, but catfish can hear very well,
or rather feel vibrations. I don't think the scent hits the fish that fast,
so it has to be sound. I know mudminnows I have kept are very keen on sound.
Once they are accustomed to worm pieces dropping in the tank, they will come
racing to the surface if you drip a drop of water in the tank.
Ray
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