Why Paint the Back of an Aquarium? Reasons and Options

The short answer

To hide what sits behind the tank (cords, pipes and the wall) and to give fish and plants a backdrop that shows off their colors. In the methods covered here, paint goes on the outside of the back glass of an empty tank. It is close to permanent, so an outside vinyl background suits keepers who may change their mind.

What a painted back does

The first reason is concealment. Practical Fishkeeping, a UK fishkeeping magazine, says dark backgrounds also do “the important job of hiding all the ugly cables, pipework and inevitable dust and detritus that sit behind the average aquarium”.

The second is contrast. Practical Fishkeeping says “dark backgrounds help ‘set off’ the plants, décor and fish”, and Bulk Reef Supply, a reef aquarium retailer, says “black backgrounds help contrast the bright colors in your tank”.

The third is upkeep. Practical Fishkeeping notes that “having your tank without a background requires an extra level of maintenance”, because “to keep it looking sharp you’ll need to clean the back glass inside and out as well as the front and sides.”

Austin Lefevre, an aquarium business owner writing for the reef publication Reefs.com, adds that his thick, poured-on coat “still allows using pumps with magnets (Tunze, Vortech, etc.) on the painted panes”.

Do fish feel safer with a background?

Aquarium sources say a background helps, and one says dark:

Practical Fishkeeping says dark backgrounds offer “a great sense of security” to fish.
Aquarium Vinyl, a maker of tank backgrounds, says a background “can give the inhabitants a greater sense of security”.
Charterhouse Aquatics, a UK aquarium retailer, says “many fish feel more secure when the rear of the aquarium is enclosed.”
Aqua-Fish.net, a long-running hobby site, says “transparent or reflective glass can confuse or stress fish, especially species prone to reacting to their own reflection.”

In a 2001 review for the Global Aquaculture Advocate, an aquaculture trade publication, Sofronios Papoutsoglou of the Agricultural University of Athens looked at studies of indoor tank color. He writes that “reactions to tank color vary with the species and life stage”, and that the studies “suggest that black tank color increases stress sensitivity, at least in those fish species studied so far.” Those studies covered whole indoor tanks and species such as eels, trout, flounder and tilapia, not a single dark pane in a home aquarium, so they neither back nor contradict the hobby advice. Treat fish comfort as unsettled.

What it costs you: permanence and light

Aquarium Vinyl, which sells backgrounds as the alternative, says “painting a tank’s back is a near-permanent solution” and that “if the paint is ever to be removed, the tank has to be emptied and drained before the laborious process of chipping the paint off with a razor blade.” Aqua-Fish.net is milder: painting “cannot be changed easily afterward”, yet it lists painted glass among external backgrounds that “can be removed and replaced without disturbing the tank.” The two sources differ, so plan on paint staying put.

A black back also absorbs light. Bulk Reef Supply ran its own test: a 24-inch (61 cm) cube aquarium with one Kessil A360X reef LED 8 inches (20 cm) above the water, and seven different backgrounds, with light-meter (PAR) readings across the tank. Black “resulted in up to 10% less average PAR throughout the entire tank”, with “up to a 28% drop in PAR toward the bottom of your tank” and “up to 33% less PAR in the back area of your tank”. These are its largest differences, not typical ones. Its advice is about corals: with “a large rock wall or pile of rock up the back wall of your tank”, the color “just won’t matter that much at all”, while for corals growing along the back wall of an open layout, “a clear or transparent background will provide you with better PAR compared to a black background.” It did not test plants. Our Lighting section covers aquarium lights.

Paint, vinyl or a 3D background

Option	Where it goes	Changing it later
Paint	Outside of the back glass	Scraping (see above)
Self-adhering vinyl	Outside only	Peels off; reusable
Printed poster	Outside, taped or glued	Easy; may bubble or peel
3D background	Inside the tank	Removal: drain some water

Vinyl. Aquarium Vinyl says its backgrounds “are self-adhering using microsuction technology” and “can be applied, removed, and re-applied multiple times”. Its instructions are firm: “All vinyl backgrounds and decals should be installed on the exterior of your tank only.” It suggests installing “on the outside of an empty tank”, but says a standing tank works “as long as you can reach the entire back of the tank (the center and all four corners).” That makes vinyl the option for a tank that is already set up.

Posters. Aqua-Fish.net says printed sheets “are usually taped or glued to the outside of the tank” and that “they often bubble or peel off over time”.

3D backgrounds. These sit in the water. Aqua-Fish.net lists their downsides as “cost, time investment, and reduced tank volume”, and says a silicone-glued one “cannot be removed without draining at least part of the water”. Universal Rocks, a 3D background maker, says to “rinse the background with a hose or power washer to get rid of excess coloring before placing it into the fish tank”, adding that “there will always be some color residue, though it is not harmful”. For a new tank it recommends “keeping the fish tank dry during installation”, and with silicone, to “let the silicone cure before adding any substrate, decorations, water, and fish”. With clips instead, it notes that “gravel will help hold the base in place” (more on what aquarium gravel does). Aqua-Fish.net says to “use aquarium-safe silicone when fixing backgrounds inside the tank” and to “allow at least 48 hours of curing time”; follow your silicone’s label too.

To install one in an established tank, Universal Rocks recommends “draining the aquarium at least half way”, and, “if using silicone, give time for the silicone to cure before refilling the aquarium.” For tanks six months or older, it suggests “doing a gravel vacuum water change one day prior to installing”. The sources do not say how long a half-drained tank with fish can sit while silicone cures, so ask the background’s maker before you start. Refill as you would after a water change: in freshwater tanks, treat tap water with a conditioner first (API, a water-care maker, says its Stress Coat “instantly removes chlorine and chloramines from tap water”); saltwater keepers follow their salt mix’s instructions.

Choosing a color

Black: the contrast choice above, with the light cost Bulk Reef Supply measured.
White or light colors: Bulk Reef Supply says it “almost never” considers them “because it will be difficult to maintain a clean appearance.”
Frosted: Charterhouse Aquatics says “frosted backgrounds create a minimalist aesthetic and can make aquariums appear larger and brighter”.
Clear: more light than black in Bulk Reef Supply’s test, but the wall and equipment stay on view.

A member of Houston Fishbox, an aquarium club forum, found that black suited cardinal tetras and silver fish, while “many blue discus tend to darken with a black background”, and suggests “buying some different colored boards and taping them to the back of the tank to get an idea” before you commit.

How to paint the back glass, step by step

This method is for glass tanks. We found no source on painting acrylic tanks, so if yours is acrylic, ask its maker first.

Paint the outside of the back glass of an empty tank

That is how the sources describe it: Aqua-Fish.net says “if you’re painting the back glass, do it before filling the tank”, and Lefevre judges the finish “from the viewing side”. None of them says outright never to paint the inside, and Krylon’s pages do not mention aquariums or say the paint is safe for fish, so paint that could touch tank water is not covered here. Nor do the sources cover painting beside a tank that holds water and fish: for a set-up tank, use outside vinyl instead.

Choose the paint with care

Aqua-Fish.net says to “use non-toxic, waterproof paints”. Krylon, a paint maker, says its Fusion All-In-One “can be used on metal, wood, plastic, PVC, laminate, glass, ceramic, plaster, and more” (its list does not name acrylic tanks), “without needing to sand or prime before using it”. Krylon’s product page says nothing about aquariums and does not call the paint non-toxic or aquarium-safe, so check your can’s label and safety warnings. Keepers name several paints: Lefevre writes, “The specific paint I use is Valspar Latex Enamel”; a Houston Fishbox member says “I’ve used Krylon and Rustoleum, they last”, and warns: “wear a mask, this stuff is MUCHO TOXIC!”; one Reddit r/Aquariums commenter (2019) says “most use acrylic paint and a roller.” Owners disagree on water-based paint (FAQ below).

Clean the glass and mask everything else

One Reddit commenter suggests cleaning the pane with alcohol before coating it. Another says to “tape it off well & seal the top up (I taped down seran wrap)”, which keeps spray off the other panes and out of the empty tank.

Ventilate

Krylon calls spraying outdoors “our recommended method because it ensures you of a well-ventilated work area.” Indoors, its FAQ says: “Open all windows and doors to ensure fresh air during spraying and drying. Use a fan to circulate emissions toward open windows and doors. Wear a painting mask for respiratory protection.” For Fusion, Krylon gets “best results when temperatures are 55° F to 75°F and humidity is below 60%.”

Build up thin coats

The Houston Fishbox member’s advice is “spray on thin coats at a time”, and “having a flashlight or small lamp may be handy, to check for areas where the paint may not be thick enough”. Wait between coats as your can’s label says: Krylon’s FAQ says to “check the label of each Krylon product for recommended dry and recoat times.”

Let it dry completely before you fill the tank

Aqua-Fish.net says to “let the paint dry completely to avoid chemical contamination”. Krylon gives dry-to-touch (about 20 minutes) and ready-to-handle (one hour) times for Fusion, not a full cure time. The Reddit commenter who suggested alcohol advises letting a coating dry “to where you can’t smell anything like 2 days to be on the safe side”. Use the label, and wait until it is dry all the way through. For drips, Lefevre says “accidents can easily be removed from glass or trim with a razor blade once dry.”

Ready to buy?

Our Substrate, Plants & Decor section covers decor, and our older roundup of black aquarium backgrounds lists background films and papers. For more setup guides, see Tank Setup & Care.

Frequently Asked Questions

Q. Can I spray paint the back of my aquarium?

Owners do it, on the outside of the glass of an empty tank: Aqua-Fish.net says to paint the back glass “before filling the tank”. Krylon lists glass among Fusion All-In-One’s surfaces but says nothing about aquariums, and recommends spraying outdoors. This is for glass tanks; we found no source on painting acrylic tanks, so ask the tank’s maker.

Q. Is it necessary to use an aquarium background?

Not always. Practical Fishkeeping says that “many of the more lush, heavily planted aquascapes offer plenty of cover and the required sense of security that means they can be presented without a background”.

Q. Can I use acrylic paint on the back of a fish tank?

Owners differ. On Reef Central, a reef forum (2017 thread), one member says “Ive had good luck with artist acrylic from the tube”, while another advises “just don’t use a water based paint.” Aqua-Fish.net names “gloss or acrylic” among non-toxic, waterproof paints.

Q. Can I change a background without draining the tank?

An outside vinyl or poster background, yes. A silicone-glued 3D background inside the tank “cannot be removed without draining at least part of the water”, says Aqua-Fish.net, and paint may need an empty tank to scrape off, says Aquarium Vinyl.

Sources (17)

Aquarium Tales Team

Written and reviewed by the Aquarium Tales Team. See the About page for how we work.