How long have you had them. Their growth rate is nothing like a common, but they do grow pretty good. You should see about an inch every 4 months. What do you feed them other than bloodworms. This is a species that is not overly excited by bloodworms.
only bloodworm ,tried prawns and cucumber, it doesnt seem interested, should have gotten a bigger one , can't wait to move him into the main community tank, what other diet can i feed ?
make sure you wash you're veggies too. my plecs eat the whole broccoli, not just the stalks. with high starch foods like potatoes i wash them thoroughly and even leave them to soak for half a day or so. its not good for your water quality