Nice to know about this little population. I wonder if any biologists/conservationists have ever heard of this population. Good to know they are comfortable even with humans around.
Have you noticed any impact on their habitat owing to the human activity around? Is the lake in general affected by garbage disposal, detergents, fertiliser run-off etc.? It might be a good idea to maintain systematic records of the same.
Catfish are voracious, hardy fish that can grow to literally uncontrollable sizes if they find the food necessary. A good population of healthy catfish will ensure large, healthy crocs! Since catfish are omnivores with a huge appetite, it is also likely that they keep the lake clean. It would be great if you could document various aspects of the lake's wildlife, so that you could try to derive (or we could discuss here) this very interesting ecology.

Thanks for sharing!