Introduction: Dark and Eerie Fish Tank

About: At home, you can find me with my wife and three boys, maybe practicing violin, guitar or piano, in the garage doing some woodworking, bicycling, at the computer, learning small electronics, video editing, surf…

A freshwater aquarium doesn't have to just be a home for fish. It can also be a canvas for a form of art if you want it to be. That form of art is called "aquascaping."

Like paintings, some of these aquascapes have names. I call this one "Is it Time to Go?"

This is an eye level aquascape: an effort to put you in the scene, standing there. For me, the aquascape is about facing death; not in the horror movie or slasher sense, but in the everyday and real sense, where people die of Alzheimer's, Leukemia, colon cancer, heart disease or simply old age. Before you is a dark path in the woods, leading to distant and unknown light. The leaves on the trees have fallen. Along the path, almost hidden in a clearing to your right, is an empty wooden swing. It seems out of place: "Why is it there?" If you chose, you can sit in the swing and experience a simple joy of life, closing your eyes and forgetting about the frightening things around or your remaining journey ahead.

In this Instructable, I'll take you back to the beginning, how the idea started and what changed along the way. I'll show you how I put together everything inside the tank, how I made the trees, the puddle, the swing and the fall-like leaf litter. I'll explain how I made the customized background, the trees and the lighting and the stand work together with the design. Of course, you could incorporate as many of these ideas into your aquarium as you want.

Hopefully, I'll introduce you to something you have never seen done with an aquarium before.

Step 1: Get Inspired to Try Something Different

Inspiration can begin anywhere. The inspiration began as I snapped the first photo in Jekyll Island, GA.

It went a darker direction after I received a Finnex Planted Plus 24/7 LED light as a gift. That RGB led light is designed for planted aquariums, has a remote, and allows for seemingly unlimited light settings. It occurred to me that many aquarists were getting these affordable and exciting lights, but only a few are exploring the idea of purposefully designing their aquascapes around them. Instead, most commonly people set up and design their freshwater tanks to be brightly lit up just they always have, but with the new technology they might dim the lights or turn on some color just for fun. "What if," I thought, "someone deliberately designed an aquascape to be displayed dimly lit in red or blue?" "What if I could make something with a darker, mystical, fairytale or erie, feel to it?"

So I went online and searched for "mystical forest" pictures, and discovered the dimly illuminated artwork shown in the second photo with a curious and contradictory element: a swing. "Swings are for happy, cheerful places," I thought. "Why would ANYONE want to sit on a swing along a path and in a place like that?" That question stuck with me, and I knew that was was the direction I wanted to take my aquarium.

Step 2: Materials and Tools

Before I go into this materials list, I want to tell you that I fell head over heels for this rimless glass cube aquarium (with the pictured stand) after seeing it advertised locally. The two polished chrome trim pieces reminded me of the aquarium my dad and older brothers kept over 40 years ago.

AQUARIUM: Custom Rimless Cube, Inches 18" tall x 18” wide x 16” deep from the wall. Approximately 20G; Centimeters 45.7 cm tall x 45.7 cm wide x 40.6 cm deep from the wall. Approximately 75L.

LIGHTING: Finnex Planted Plus 24/7 LED Light with Remote (the main light) - from · Meridian Soft White LED Directional Night Light (for moon effect) - from Dollar General. · Meridian Soft White LED Standard Night Light (for mysterious glow effect) - from Dollar General.

BACKGROUND: Custom made cling background using a camera and Photoshop. Printed at

TREES: Manzanita wood (not sandblasted) - from · Crafted using hobby saws, hobby sander, super glue gel. · Some trees attached to slate tile with stainless steel screws.

SUBSTRATE: Black diamond blasting sand 20/40 grit (used as a base substrate) - from Tractor Supply Co. · Black Caribsea Flouramax Substrate (used for cap) - from local fish store · Red Eco Complete Substrate (used with strainer to create leaf litter effect) - from local fish store.

FILTRATION, CIRCULATION & HEAT: Tom Aquatics Rapids Mini Canister Filter C-80 (modified by replacing hoses) - from Amazon · Two (2) Mini submersible aquarium pumps. 80 GPH each - from Amazon · Submersible aquarium heater - from Amazon.

DECORATIVE ROCK: Seiryu Rock - available on eBay. Dark grey slate tile & super glue gel (for making rock silhouettes) - from Menard's.

SWING: Polymer clay, such as Sculpty - from craft store Michael's; twine from local hardware store.

POND & LIGHT RISERS: 1/4" black, gloss acrylic - from local acrylic shop · All designed on Inventor, the laser cut. Light risers glued using acrylic adhesive - from local acrylic shop.

STAND · Live edge Black Walnut slab - from local mill & blackberry farm. · Treated bark with CA glue - from HobbyTown USA . Coated with semigloss polyurethane · Antique sewing machine base

FISH · Ember tetras (planned) - from local pet shop or online.

Step 3: Make Trees From Manzanita

This was my first experience working with manzanita wood. I purchased it online from Although available sandblasted, for the dark look of this tank, I wanted wood with the bark still on it. Buying manzanita wood online is not as difficult as you might think. I sent my inspirational artwork and tank dimensions to through Facebook messenger. They responded back with photographs of several pieces that would work, and gave me a price. It arrived carefully packed and undamaged.

I had watched a video tutorial on how to make trees from Manzanita driftwood. Starting with a main tree branch, I added multiple other smaller branches with super glue gel to fill in the spaces of the main tree. I worked very slowly and deliberately, checking the tree against the tank and against a light to achieve the desired spacing. A small hobby saw and electric belt hobby sander were helpful, if not necessary, to carefully match new branches to the curved surface of the main tree. As much as possible, new branches were added to the back side of the tree so the seams were hidden. Rather than cutting branches off the top, I tried to use the naturally weathered ends. If necessary, rather than cutting the tops, I broke them off.

I used plastic zip ties, tape, and sometimes an extra set of hands to help hold the pieces together while gluing and until the super glue gel cured.

Step 4: Using Slate Tile

I attached these two pieces of wood to a natural slate tile. This not only keeps them from floating, but also positioned in exactly the spot and angle I want. The small tree fits into a hole I drilled into the slate and is held with super glue gel. The large tree trunk is attached to the slate using a stainless steel screw through the bottom of the slate and up through the center of the tree trunk. In addition to drilling a pilot hole, I chipped out an area on the underside of the slate to make room for the screw head so it would not place pressure on the bottom glass.

Step 5: Tree Magnet

The main tree is the only obstacle to full access to the inside of the tank, but it's a significant one. I knew that occasionally, I would want to remove it to get it out of the way and then put it back. I wanted it to snap back into a very specific spot without having to readjust the angle or worry about it tipping over. It turns out that not a lot of people have this issue with their tanks, so I had to do my best to come up with my own solution.

Then I thought, "waterproof magnets are already used to hold some heaters and other equipment to the glass."

So, I used the a heavy duty magnet I found at a hardware store, and coated it and all of the parts in aquarium safe epoxy to make them waterproof, and attached the magnet to the tree with a stainless steel screw. The slate piece would later be lightly attached to the bottom glass using aquarium safe silicon.

Step 6: Rough Draft

I gradually laid out a rough draft of the aquascape, checking the position and angles of the trees and branches. I verified that the tree trunk on the left was doing an adequate job of blocking the view of the back left corner where the heater, filter intake and circulating pumps would be hidden from view.

After getting the trees close to how I wanted them, I added some of the black substrate I intended to use (flouramax), the seiryu rock, and a temporary puddle made from cardboard. Viewed from the front, the inside lines of the trees, the rock and even the puddle formed a circle, and I tried to lock the lines onto that shape. I could also start to see how using the larger trees in the front and smaller ones in the back was starting to create the sense of depth that I was wanting.

At this time, I was still planning on adding plants, so I was saving room for them.

Step 7: Custom Backdrop

Meanwhile, I needed to work out what to use for the background. I went to a local theatre production of "Oklahoma!" and was reminded of how much stage designers could do with a simple painted backdrop just by adding light to the front or back of it. I decided I would spend a little more and make a simple custom backdrop using that concept.

So using my cell phone camera, I took took several photos of clouds outside, looking for a shot that would place a "brighter center" in the right spot of the rough draft of my aquarium. After snapping a favorite, my son used photoshop to add more contrast to the photo, and added a "twist" effect that would help add mystery and blend it into the path.

I uploaded the custom backdrop to for printing of a "cling on" backdrop.

Step 8: Underwater Puddle

I bought a scrap piece of 1/4 inch, glossy, black acrylic. Using the cardboard puddle as a guide, I drew out the main puddle on the computer using Inventor. I made a few extra, smaller puddles just in case I wanted to use them (I ultimately did not).

The puddles, and the acrylic riser pieces shown in the next step, were cut using a laser cutter/engraver at our local public school.

Step 9: Raise the Lights

As manufactured, the Finnex Planted Plus 24/7 LED light rests only about 2 inches (5 cm) above the surface of the water. I believed the overall presentation of the tank would look better if I raised the light above the treetops. This would have the effect of highlighting the treetops, dimming the light, and moving the light away from the background. I made two 8.5 inch (21.5 cm) light risers out of 1/4 inch acrylic (the same thickness of the glass on my rimless tank). For each riser, I attached two of the smaller pieces, one on each side of each riser, using a special acrylic adhesive.

Step 10: The Swing

The swing is a somewhat hidden focal point, especially with the lights very low. Following the rule of thirds, it is positioned so the swing rests 1/3 from the bottom and 1/3 from the right of the tank.

The swing board needed to look like wood but not float like wood. So I looked for an aquarium safe material I could use to make something in the shape and color I wanted, easily drill holes in it, and would sink. i discovered polymer clay sold at craft stores.

I read everything I could find online about whether polymer clay is aquarium safe and came to these conclusions (1) polymer clay is essentially PVC, and PVC is already commonly used in aquariums, (2) polymer clay is not food safe, but the reason is because it is porous and therefore cannot be cleaned thoroughly enough, it is not because of its chemistry, (3) it has a moistening agent that dries as the clay is baked, so I knew I would need to bake it thoroughly, and (4) unlike those who have tried to make entire 3D aquarium backgrounds and reefs out of it (imagine the difficulty of baking the moistening agent out of something like that), I was only going to use an extremely small amount of it compared to total tank volume.

I made several samples. To get a lighter color for the swing board, I twisted and slightly blended two colors together. I etched wood grain lines, cut to shape, baked according to directions and drilled holes for the twine.

Step 11: Make a Stand

The wrought iron base of this antique sewing machine has been in our family for years. While I was growing up, my dad even used it previously as an aquarium stand, except he had a school desktop and drawer combination for the top. I wanted to replace the top with something more natural which would match the look of the tank. I bought a slab of live edge black walnut from a local mill and blackberry farm. After I picked one I liked, they planed it down to 1 1/2 inches, and threw in a quart of blackberries

I cut a 30 inch portion off the end, cleaned the bark edge and sanded. I read about numerous methods for finishing it, and decided on reinforcing the bark edge with CA glue. I continued to sand the top to 220 grit, then finished the top with a high gloss poly, and painted the underside black.

Step 12: Pad & Power

I cut two pieces of bathtub liner to serve as a small pad between the tank and the bottom glass of the tank, helping reduce nonuniform pressure from any minor imperfections in the stand surface.

The second photo shows how I hid the power strip.

Step 13: Attach Background

I found that the custom background was easier to center if I trimmed it back a little on each side.

I attached the backdrop using one of a few popular methods. I laid the tank face down on the floor, wiped vegetable oil on the back of the back glass, then placed the background on. I used a squeegee or similar flexible edge to work out the bubbles under the backdrop, periodically wiping off the vegetable oil as it pushed out the sides. As people who have done this would know, it takes patience, and going back over it again even an hour or day later, as bubbles have a way of regrouping or showing up again.

When finished, I put the tank on the stand and snapped this photo.

Step 14: Start the Final Draft

Then I started the final draft of the scape. At this point I attached the slate base of the main tree (the one with the magnet) to the bottom of the tank with a small amount of aquarium safe silicon.

To build up the substrate depth, and because I was still considering planting the tank at the time, I started with a base of thoroughly rinsed, 20/40 grit black diamond blasting sand, I tried to keep the sand away from the area where the main tree would attach. I continued to add the other elements to the scape.

Step 15: Add More Manzanita & Leaf Litter

Around this time I was posting photos of my tank in progress on social media. Several things happened from the feedback I was getting.

First, I decided I would leave the tank unplanted. Plants would not only be difficult to maintain in a tank with limited access, the creepiness of this aquascape was something people had not seen before. But, without adding plants, the tank needed more volume of wood, and by doing that, I could also improve the sense of depth. So, I ordered another box from I added the tree trunk in the foreground on the left, three small trees in the back right corner, added more rock, among other changes.

Also thanks to another great suggestion, I experimented with and ultimately added a leaf litter effect. To create that, I bought a bag of substrate (Eco Complete). The color I bought is technically called "Red" but to me looks like a mix of substrate in fall-like colors. After thoroughly rinsing and drying it, I sifted it through a strainer to separate the large pieces from the small ones. I scattered the large pieces in the foreground, and used the smaller pieces for the more distant leaves in the back. Imagining where leaves might collect or blow away, I left some areas relatively untouched, while in other areas I literally dumped piles.

Step 16: The Lighting

The main aquarium light above the tank is a Finnex Planted Plus 24/7 LED light. It has a remote and has multiple programmable settings, including one where it gradually changes color and brightness to simulate the hour of the day.

In addition, I purchased a directional LED night light and a more traditional LED night light that diffuses light generally. I experimented with placing the lights behind the background. The directional night light was effective for creating the moon. Just to see what it would do, I tried taping a coin to the face of the night light, which worked to create different phases of the moon. However, with the cloudy night scape I was creating, I decided to stay with a full moon.

I used the more diffuse LED night light for the erie glow down the path. I arranged the equipment, power strip, cords and tubing behind the tank to allow the lights to shine on the background without any obstructions.

To create the smallest and most distant tree, I started with a photo I had taken of the main tree. I used a photoshop to turn it into a silhouette, reduce the size, reverse the direction it was facing and, most importantly, add a blur effect so it would appear out of focus. I printed that blurry tree silhouette on a clear transparency, then stuck to the back side of the backdrop. Now when the nightlights come on, that distant tree seems to appear in the fog.

Step 17: Stock With Fish

If you look at the first photo, I think you'll see what I mean when I say that access to the tank is very limited. Purposefully, I wanted to make sure that 95% of what is in the way comes out when the main tree, attached with the magnet, is removed. That makes it easier than it would have been, but I still don't want to do that very often.

Aside from the point that you should pick fish appropriate for the size of your tank, I did not want to get fish that were going to require me to take the main tree out very often. Some fish like to dig around in the gravel and would destroy the tank. Some fish, like mollies or guppies, breed prolifically. Others generate a lot of waste. Neither of those things would be good for a tank I cannot access easily.

Some fish are more notorious for jumping out aquariums without lids. Also, the tank is kept fairly dark, and I want something I can see. Ultimately my plan is to get a school of ember tetras.

I decided on a male betta, a school of ember tetras, and a few oto cats to keep things tidy.

Step 18: Is It Time to Go?