i kept a grey bamboo for a decent amount of time( hes only gone because i had to relocate for work or iw ould still have him). when i got him he was only about 8-10 inches.. a year later he was over 18- 20 and it was time for me to upgrade already.. THUS dont waste your time just get a 4-500 gallon( or at leat an 8 foot long tank by 4-5 foot wide if not he will be very uncomfortable after evan a years time if fed properly!!!.. and make wise tankmate decisions because grey bamboos are straight NASTY when they feed.. i would have at least 1 injury in my tank almost every feeding until i figured out how to avoid it...
also the above post from you is not a good one.. you cant "tach" a shark how to eat right and how to burn less calories ina big tank... they should be eating like pigs and swimming alot,, thats how you know you have a happy shark..
sharks, once again if fed properly and housed int he right size tank from young IMO will grow VERY fast and VERY quick, just like they do in the wild
also grey bamboos are extremely hard to find, but if you have a source thats good.. dont let someone tell you its a grey and its really another type of bamboo shark..