The longhorn cowfish do get quite big fast.
With my helmet cowfish though unless a thornback has not grown that much in a years time. Mine was quite small & now is an inch or too bigger.
hey albert_dao, curious what you feed your cowfish that got good growth in 8 months. I've been wondering why mine hasn't gotten bigger...maybe due to diet?
Also what size tank did you have it in? I always love to here others that have had great experiences with these fish.