The Pet house is paraparaumu is the only marine retailer at the moment as far as i know; has marine gear e.g. live rock some fish and corals etc aswell as equipment.
Animates Kaiwharawhara and Lower hutt have basically the same selection, the hutt one probably has more fish in my opinion, plants are mostly the same some are hydroponically grown aswell which can cause issues with changing to being submerged.
Hutt pet centre is my favourite theyre changing their set ups soon having a bunch of new and larger tanks installed aswell as getting some marine set ups, they also have some tropical and freshwater plants but i have never really looked into buying any from there, nice selection of fish etc aswell; Also you get a 10% discount if your with a fnzas club etc.
AnimalZ is Petone is getting into fish, last time i checked (start of april) they were just waiting on the builders to finish in a new building across the road from their current location which was guna have a bunch of newly built tanks in, lots of different kinds including marine which will be good for everyone
Theres a few other stores around the place not so much on porirua side, theres Wainui Pet & Farm Supplies and one in Upper hutt if i recall correctly which i havnt visited yet (they should be in yellow pages), thats about what i know hope it helps :bounce: