I'm Trying to find a way to Record it, but I am leaning twords the Chocolate Catfish with this one, We've had them for the longest and the noise has been going on for awhile. I know the clown loaches we have made/make noise now that Roan posted the links up there,
i had my angelicus pictus for a few years before i ever heard it "vocalize." it happened when i netted it (like an idiot...had to cut the net since at the time i didn't realize it had spines behind its gill plates). it made the cutest sound though memory fails me what it was. it may have been a "trilling" or a "cooing" type sound.
its name was gabriel, btw. trying to do a search but my computer won't cooperate!
Thats actually kind of funny that this was brought up because today for the first time I heard my yo-yo loach making like a snapping sound when he came to the top of the tank to eat. I've had it for at least a year and I have never heard it until now. I guess it was because I just dropped the first bit of flakes into the tank instead of holding them under the water for a second for them to drop down. The yo-yo came up and every time he came all the way to the top and bit on a flake, I heard the sound. It was pretty cool.