Mine was about that size, maybe a touch smaller when it passed, about 22 months old. I have seen one around 8ins and 5ish yrs old. Thats pretty rare though.
Mines around 6-7 inches now and he's a beast!! His fins are super long and I can't believe I got him at petco when they had the 50% off deal so I ordered him and got him for $30... About 8 months ago I bought 8 small ebjd and only two made it pass 4 inches and hopefully I can post a pic so you guys can help me determine if male or female... I'll post tonight!!!