The mudhopper story I heard was a south American white catfish, the angler put it down on the banks and it ran through his legs, off down the banks, he chased it for a while and it eventually dived back into the canal.
I have an old article in Freeline magazine somewhere, that was the NASGs magazine, it was written by me old mate Ron Pendleton of the St Helens Freshwater Study Group and is about the Hotties and the Chillids, ca 1975