I've had mine for about the same, what size are they, mine were juniors when I got them and they are around 6" long at the moment, so along way to go yet. I have found mine are pretty well bomb proof, they have out lived everything else. I have three, two have kept their stream like shape while one is plumper and larger, so assuming this one is female. I will be interested also if any-one has an answer to your question.
silver or bala sharks can live for 20 years or more. They can reach 12 inches long (sometimes more) and are pretty tough once settled into a tank. Sexing is the same for most barbs and rasboras, with males being smaller and slimmer while females are larger and fatter, (like Littlemonkey said )
Thanks Colin_T. Yes they are tough critters. They do like to jump however, so a tight fitting hood is advisable. It's remarkable how they don't brain themselves. Also they grunt. I love my three, still after all this time I can't think of any suitable names for them.