Not at all surprising. A 2 - 3 inch Channa gaucha is just another snack for a 7 inch Polypterus weeksii and one that is perfectly shaped for easy swallowing at that! Sorry you had to find out the hard way.
I'm assuming that Mangch1 is aware of the legal status of Channa species in California and has chosen to keep them regardless. That point being made, it would probably be a good idea to remove any other similarly-sized fish from the tank with your Polypterus weeksii as soon as possible or they're likely to suffer the same fate as your C. gaucha. krndude610....everybody makes mistakes at one time or the other and only become a 'freakin idiot' if they make the same mistakes over and over again. Let's not be harsh in our condemnation of others. Hopefully there was a lesson learned here and we can just leave it at that.