If it is thirty inches, it must be atleast a decade old, cause my protopterus annectens annectens, which is the exact species as yours, was 19" when I got it way back in 2009. It is an inch less than 30" now,
My guy gets very less Pellets and more of fruits such as banana and papaya, spinach and fresh water Tilapia with spine and scales, and he his favorite is apple snails, which I give him as treats.
Although my guy, doesn't like tank mates, as he has devoured quite many plecos, before I gave up on the idea, also doesn't like being handled, I have seen him snap at nets and hoses, so I don't try my luck