It dies look like he's swallowing a meal. With that in mind I'm gonna say he's laughing at you because knowing catfish, he probably at an expensive tankmate. Never trust a catfish!
Also, I'd like to point out that fish isn't B. flavicans. Flavicans was a synonym used to refer to multiple Pimelodid species to include this fish and both Jaus, so a revision in (I believe) 2009 clarified the issue and assigned this fish the name Brachyplatystoma rousseauxii. B. flavicans is no longer a valid name for any Pim.
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