Brick Aquarium MOC Build Guide: Reef Tank to Tunnel Exhibit

Of all the scene categories builders take on, a brick aquarium MOC is the one that shows off clear-piece skills the most. Deep-sea blues, a huge tank glowing from within, fish drifting through it — it looks stunning before you have placed a single brick. Best of all, the scale is flexible: a beginner can start with one standalone tank, while an experienced builder can turn the whole thing into a landmark that fits a modular street. This guide breaks the design down from the tank body to the individual exhibit halls.

1. Base and Color Palette: Set the Mood of the Water

An aquarium's character comes from color. For the base, mix dark blue and light blue across the surface to suggest shimmering water, then add a small amount of sand-colored pieces around the edges for reef rock and shallows. Keep the palette disciplined: large areas of dark blue as the ground tone, white and silver-grey for the exterior walls of the building, and coral red or fluorescent orange only as accents. That contrast is what gives you "quiet deep sea inside, bright exhibit hall outside."

For the base structure, start with one large baseplate, then frame the building outline with thick plates and leave recessed slots inside for the tanks to drop into. Don't forget a small equipment room in one corner — tuck in a few grey machines and pipe pieces. Plausibility usually hides in the corners nobody photographs.

2. The Reef Tank: The Star of the Show

The tank is the heart of a brick aquarium MOC, and it makes or breaks the build. The core technique is heavy use of transparent pieces: build the four tank walls from transparent panels or large clear windows, back them with a blue backdrop panel, and run a row of transparent light pieces along the top so the light "passes through" the water. The tank instantly reads as glass with water in it.

Inside, lay a sand-colored baseplate first, then build up the reef: stack small red and pink curved pieces into coral heads, use green branch pieces as seaweed, and blue curved plates for the sweep of a current. Hang or attach fish pieces at different heights in the tank — the uneven spacing is what makes it feel alive. If you want to push further, add a ring of blue and white light strip around the top of the tank plus a few bubble-shaped transparent pieces to recreate the look of an air pump bubbling away.

3. The Tunnel Exhibit: The Most Memorable Photo Spot

A walk-through underwater tunnel is the soul of the exhibit hall. Build the vaulted roof from transparent curved pieces, extend semi-circular glass walls down both sides, and fill the space with sharks, sea turtles and schools of fish. Minifigures standing inside looking up give the scene real impact. One build tip: assemble the tunnel skeleton from dark grey or black pieces first and only then attach the transparent cladding on the outside, otherwise the structure will fall apart on you.

Lighting is what makes the tunnel work. Hide warm white light pieces inside the arch, run a dark blue light strip along the floor to fake the play of light underwater, and add a few diagonal "light shafts" made from long transparent rod pieces so it looks like sunlight is cutting down through the water. At the far end, tuck in a semi-open viewing platform where visitor minifigures point at things through the glass — the scene immediately gains interaction.

4. Jellyfish Tanks, the Dolphin Theater, and Finishing Details

Beyond the main tank and the tunnel, two or three supporting exhibits make the building feel full. A jellyfish tank is built by stacking small transparent canister pieces, placing umbrella-shaped transparent pieces inside to stand in for jellyfish, and lighting it from above in purple-blue — instantly ethereal. For the dolphin theater, use blue and white curved pieces for the seating tiers and the pool, then stand a dolphin mid-leap in the center for maximum motion. A souvenir shop, informational display panels, and a keeper minifigure pushing a bucket on a trolley are the details that give the whole building some human life.

Don't rush to cap the roof at the end. Wire every light piece in the building to a single switch, kill the room lights at night, and flip it on — the whole brick aquarium MOC turns into a genuine deep-sea hideaway. For build order, work outward from the base, to the large exhibits, to the small ones. Sort your parts into separate boxes for transparent pieces, blue-family pieces and decorative pieces; you will save yourself a lot of hunting. And if your aquarium is destined to become a landmark, feel free to browse BrickPlans for a complete aquarium instruction set to work from — it will save you plenty of trial and error on both color scheme and structure.