Animates in in Moorhouse Avenue. If you head up Columbus and turn right into Moorhouse you will see it on your left in the Mitre 10 building.
The rest are all spread out in the suburbs, not in the city centre. If you can, get to Redwood Aquatics, opposite the Willowbank Wildlife Park.
Organisms, which is on the corner of Clyde and something else (can't remember- Illam St I think). The Fish Tank in Stanmore Rd, Petworld, 475 Ferry Rd. and Critter Kingdom in Blenheim Rd.
Water World in Blenheim Rd is interesting too. They specialise in pools and equipment and have a lot set up and planted on site.
Have fun.
Grant and I are attending the Dunedin Tank and Pond Crawl this weekend and are taking a couple of other club members with us. We pass through ChCh on Friday and back Sunday.