Given enough room and space, Cats can probably grow to massive sizes. In the reservoirs here, Hemibargus Wyckiodes gets up to 6 ft. And there are a bunch of MGCs in those reservoirs that have yet to be caught. Those waters are very deep and very wide, and im sure that possibly sometime, a massive MGC might be reported from there.
Well even if they were caught, the locals care more about food than world records....