Perhaps not a huge selection of seafood choices but Flourish BBQ on Dundas a couple of blocks east of Spadina has a set dinner menu that is fresh and economical for a casual family/friend dinner out.
It's very Cantonese style where you get a list of dozens of dishes and you pick a number for a set price, e.g., 4 dishes for $29.99 that comes with daily Chinese soup and a cup of house-churned soybean milk. The dishes are of generous portions, and you can literally feel the "wok air" (Chinese reference to the flavour of the cooked food) in each plate. I usually order a fresh steamed fish, which is caught from the tank and steamed to order.
I took a group of three friends once and the four of us had steamed fresh tilapia, four combo BBQ plate (BBQ pork, roast pork, roast duck), braised eggplant and chicken, and baby bok choi with shitake mushrooms, plus 3 bowls of rice that we can barely finish, all came to $10 each after tip and tax. We were all stuffed. Now that's a deal!
Obviously there is no ambiance, and it seems like an unlikely place from first sight for a good dinner since it is mostly known for take-out Cantonese BBQ meats. But it's great for a good, hearty, authentic, inexpensive Cantonese family style dinner. The only thing is the list of dish selection only comes in Chinese so you will need to bring a friend who can read.
if i was going out for a family dinner in chinatown, i would pick rol san (east side of spadina, few blocks north of dundas).
i dont know how others feel about this place, but my husband and i have been going there for years and love it. we especially love the brisk, almost indifferent service - adds character.