omtay606 - that tig looks almost like it's short bodied. Do you have any other pics of it? Definitely healthy looking!
I personally wouldn't feed blackworms if your tig will eat anything else. They're expensive when compared to other foods, and can possibly bring other things into the tank (I've never seen a blackworm culture that was strictly blackworms and nothing else). I brought in 14 tigs at one point, all 4-6", and I fed them chopped nightcrawlers, chopped shrimp, and mysis. I fed every other day to every three days, and they all grew 1/2-1" a month. I kept 3 for myself that are all 10-12", and they're fed shrimp, nightcrawlers, squid, and scallops (whatever my rays don't get they get). Because the rays are fed every day, the cats are as well.