Why do salmon tail catfish make a gulping noise when they swim around the tank?

Question

I recently owned a large size one and it made noises. It was quite loud.

Answer 1

I've never kept these myself, but searching for some info online, it seems as through these are able to make sounds using their pectoral fins: http://www.wetpetz.com/salmontail.htm Unfortunately, the link doesn't give the reason for making the sound.

These aren't the only catfish capable of making noise, either. Spotted and striped raphaels are known as "Talking catfish" because of noises they make.