That one is called Bigmouth, narrated by Rod Serling right?
Nat Geo has their "Hooked" series which is interesting, it pertains to fishing both salt and fresh but features some impressive monsters. Nat Geo also has the Monster Fish of the...Congo, Mekong and Amazon. http://channel.nationalgeographic.com/series/hooked/all/Overview
Occasionally Animal Planet has a fish show, needless to say the new series River Monsters but there are a couple with Nigel Marven about Piranha and Electric Eels.
The VS. channel has The Hunt For Big Fish with Larry Dahlberg, lots of large freshwater species being caught on that one. http://www.huntforbigfish.com/
"Secrets of the Golden River" is another great one about the amazon with great leaping arowana footage. That one is put out by ABC's World of Discovery
PBS's Nature has one on the life cycle of the sockeye salmon called "Miracle of the Scarlet Salmon".
"Jewels of the Rift" is another Nat Geo about the cichlids of lake Tanganyika.