Under The Sea Aquatics – Bring the Ocean Home

Family-owned in St. Catharines. Tanks, fish, plants, and expert help to build your dream aquarium. Shop Supplies • Visit Store • Water Testing

About Us

Under The Sea Aquatics – Build a World Under Glass

Premium tanks, filters, live plants, and healthy fish — plus water testing and setup support. Shop Tanks • Book Water Test

About Us

Under The Sea Aquatics – Small Shop. Big Ocean Energy.

Family-run, community-loved—everything for aquariums plus personalized service. Browse Products • Visit Store

About Us

Explore Us

Welcome to Under the Sea Aquatics

We’re a family-owned aquarium shop in St. Catharines. From premium tanks and filters to live plants and healthy fish, we help you build a beautiful, low-stress aquarium—plus guidance on setup, water care, and stocking that works.

Water testing & honest advice
Starter kits to custom builds
Live plants, hardscape & décor
Setup, aquascaping & maintenance

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our Services

Our Awesome Services

Water Testing

Bring a sample—get fast, accurate results and a simple plan to keep your fish thriving. Icon idea: beaker/water-drop.

Starter Setup

Tank, filter, heater, substrate—plus friendly setup guidance.

Aquascaping

Natural layouts with wood, stone, and plants for a living showpiece.

Maintenance

Scheduled water changes, glass clean, and filter care.

Custom Tanks

Built-to-fit aquariums for homes and businesses, installed right.

Plants & Rock

Fresh plants, driftwood, and stones—hand-picked and easy to keep.

Healthy Fish

Carefully sourced and observed so you take home stress-free fish.

Reef & Saltwater

Corals, fish, and gear—We set up, cycle, and tune your reef for stable, vibrant growth.

Testimonials

What Clients Say?

“Great people, knowledge, and fair pricing. Good selection of freshwater fish and saltwater fish when available. Corals are also available for sale. Fish are kept in individual tanks, with each tank having its own filtration system… Beginner or expert, you can’t go wrong dealing with this business. A real gem. Some of the fish, etc., I purchased there.”

Paul

“This was my first visit to the store, i was pleasantly greeted by the new owner. I was impressed with the variety of both saltwater and freshwater fish, corals and even vampire crabs. For being a smaller store, they had a wide variety of aquariums, accessories as well as parts for your filtration system. They have very competitive pricing, and had exactly what I was looking for. I will definitely be returning.”

Kim Stevenson

“Kayden Was Absolutely Awesome…He’s Friendly, Very Knowledgeable, Genuine, And Really Cares For The Fish And Aquatic Life!!! Definitely Recommend Coming Here!!! Thank You For An Awesome Experience Kayden!!!”

Michael Marcolin

“Today was my first visit to this wonderful store. We were greeted by 2 staff members and 1 young man (sorry, I didn't get his name) spent so much time talking to me about my new aquarium setup and the issues I am having with my plants. I am a first time aquarium owner and still have no fish. I want to make sure my setup is spot on first. He was patient, extremely knowledgeable and is genuinely excited about what he is doing. I was thrilled to find this fabulous local spot and won't have to travel to Hamilton or Burlington anymore for plants. When it is time to add fish, they will be coming from this shop also.”

Helen Brennan

“One of the best petstore in niagara region if not ontario. Staff are super helpful and friendly. Lots of fish and equipment available.”

Natalia Ospina

“A local gem! Hubby came in this afternoon and was really impressed with the store and knowledgeable staff. The store and tanks are the cleanest he's ever seen! They obviously care about their fish and aquariums. Can't wait to bring our boys to check it out. We will be regular customers.”