Some may some may not. My congicus has been in captivity for almost 3 years and is only 16 inches while some others have exceeded that. Someone gave me some good advice buy a group and keep the one with the best appetite. Also id try for a larger tank so the fish has more room to grow my congi is really active and uses all of my 8x2 footprint
i doubt he would reach 36inches especially in a 4ft pond. i hope this is temporary housing for him as i'd suggest at least 7x3x2 for a bichir that size
Not likely IMO.
The big 30"+ Congicus and Ansorgiis you see on sites here in Japan, are usually caught fr the wild at that size, and are usually pretty old.
They wil have short growth spurts up to the 20-24" size, then it's a real slow down.
Biggest Congicus grown in captivity, I've seen so far is 30". Someone I know has grown a 7" to 29"-30" in 8 years. Another person grew theres from 7" to 30" in 5-6 years.