Great looking giraffe cat, looks like you have an auchenoglanis wittei. They do grow very fast, I've raised two in recent years, a female and more recently a male, had to sell 'em when they reached 18" which was too big for my tank. The last one grew from 1 1/2" to 12" in the first year. A. wittei will grow to 36" over time. One of my all time favorite species...