With the technology becoming better and their prices always on the decline, more and more folks nowadays own a 3d printer. These devices come in handy for everything from printing funny gag gifts to home organization—but did you know you can also print accessories for your marine aquarium? Various filaments are completely safe for underwater use, including in saltwater.
Need a fish feeder? Some faux marine rocks? Coral plugs? Pest traps? You name it, someone’s designed a print for it. No more overpaying for simple accessories: just make them yourself at home. In case you need some inspiration, I’ve gathered 20 designs you may find very useful (not to mention fun!).
3d prints for fish feeding
Nori clip
If you keep herbivorous fish, a sturdy clip for nori sheets and lettuce is a must-have. They struggle to graze and tear at the food if it’s left free-floating, and clean-up can be a hassle when pieces of greenery are blown all over the tank.
There are two basic nori clip designs. One resembles a clothespin and is suitable for fish that can be trusted not to tear off the whole sheet at once (pictured here in its unassembled state). The other uses a mesh grid, which helps ensure no single fish can make off with the majority of the food—perfect for boisterous tangs and other hungry nori hoggers.
→ Print a clothespin-style nori clip
→ Print a grid-style nori clip
Feeding cone
Most saltwater fishkeepers regularly feed frozen foods, like mysis and brine shrimp. A feeding cone comes in very handy for this. If you just throw the food into the tank, it can be blown all over the place, sending fish scrambling for a bite and possibly getting stuck in inaccessible spots to foul the water.
None of that with a feeding cone, in which you can place unthawed cubes of food to be released slowly and in a somewhat more controlled manner. This also makes it easier to observe whether all of your tank’s inhabitants are getting their fill.
Feeder ring
Floating fish food flying everywhere? It happens, especially because we saltwater fishkeepers work hard to keep the flow level high in our tanks. If you think your fish may be struggling or just want to keep things as organized as possible, a floating feeder ring is the perfect option. This is as simple as it gets: just a ring that floats at the surface and keeps floating pellets or flakes in place.
The design for this ring in particular is pretty nice in my opinion. Instead of floating freely, it attaches to the tank glass, with a handy mechanism that ensures it works for all water levels.
3d prints for corals
Frag plug
Why buy frag plugs when you can print ’em by the dozen? The slightly textured surface of plugs printed at ~0.2mm layer height is perfect to give coral glue something to grip onto, ensuring your frags aren’t going anywhere any time soon. Keep it matte for the best results—you don’t want something glossy and smooth.
This frag plug allows you to choose between a round and square design. Of course, the size can be adjusted based on the size of the frags.
Frag plug holder
Printed a frag plug and attached your coral to it? Great. Now you can install it on this frag plug holder! The natural design makes this print a nice and unobtrusive choice, especially once it becomes covered in (coralline) algae.
This frag plug holder is easy to adjust based on the size of the frag plug(s) you’re using. The open bottom allows water to get in, ensuring the holder sinks.
Frag rack
The frag plug holder above is a great, subtle solution for a single coral frag. But who has just a single frag? Not me. So here’s a heavier-duty solution for my fellow coral hoarders! Each hole holds a standard plug, meaning this rack is suitable for up to 13 frags at a time.
After printing, all the frag rack needs are a few magnets to attach it to your tank, and you’re good to go.
3d prints for aquarium organization
Filter media basket
Filter in need of some organization? Many models only offer limited options for combining different kinds of filter media. Luckily, printing a filter media basket is a breeze, as you need little more than boxes that water can flow through.
The media basket pictured here is designed for the Fluval Evo 13.5, but it can be customized to fit a variety of other filters. If it doesn’t match your filter, search for the model you own—someone may already have designed one for the specific brand.
→ Print aquarium filter media basket for Fluval Evo 13.5 gallon (or search for other designs)
Test tube holder
This print cracks me up because it’s like it was designed for me! If you recognize the struggle of test tubes all over the place, not remembering which is which, and even knocking them over on occasion, this one’s for you as well.
The holder pictured here is meant for test tubes from the Hanna brand of water test kits, but it should fit many brands—you can adjust the size if the holes are too small.
→ Print aquarium test tube holder
Cable holder
Aquariums are full of cables, especially in the saltwater hobby. Even my 10-gallon reef tank, which is devoid of fancy wavemakers and automatic feeders, comes with no less than five electronic devices: heater, filter, skimmer, white light, and blue light.
That’s a lot of cables, and they drive me nuts! Or they used to anyway, until I printed a bunch of cable holders/guides. Now they stay in their designated place, and the spaghetti behind my tank is much more streamlined. One of the best 3d prints for aquariums in terms of the amount of filament used vs. usefulness.
→ Print aquarium cable holders
Tube guide
You know what’s worse than cables? Tubes. They get mixed up, they get kinks that obstruct water flow when you trail them over the edge of the tank glass, and they’re just generally ugly and all over the place. Unfortunately, between filters, sumps, water change hoses, and other equipment, our tanks are pretty stuffed with them.
This very simple tube guide print has been a lifesaver for me. No more buying U-attachments to prevent kinks, and all those pesky tubes stay exactly where I wanted them to.
3d prints for aquarium cleaning
Algae scraper
I’ve tried an incredible amount of different algae scrapers over the years. Aquarium writers get to test a lot of equipment! There’s magnetic cleaners, sponges on sticks, and more brushes than you can imagine, but none have worked as well for me as a simple razor blade—at least on glass tanks, don’t try this if yours is acrylic!
Nowadays, I mostly use this simple 3d-printed attachment. All you have to do after printing is slide a disposable blade into it, and you’re ready to go on the offense against pesky (coralline) algae.
→ Print aquarium algae scraper
Gravel vacuum attachment
Our tanks—especially the substrate—are dirt magnets. No problem for these gravel vacuum attachments, which are narrow enough to remove leftover food and other debris even from the tightest corners. These would work particularly well in bare-bottomed breeding and rearing tanks!
If you already have a gravel vacuum, like the popular Python, be sure to print a cover for it if you haven’t already—it’s all fun and games until your expensive fish gets injured during an unintended ride up the cleaning tube and into the water change bucket.
→ Print aquarium gravel vacuum attachment
Miscellaneous accessories
Random flow generator
As I’ve touched upon, we saltwater aquarists just love flow. It keeps our corals healthy and prevents dead spots. And did you know you can make your filter’s outflow that much more efficient by adding a random flow generator?
The ever-changing water movement generated by these simple nozzles ensures water is truly blown all over the place, creating an aquatic “breeze” in even the most difficult-to-reach nooks and crannies.
Acclimation box
In saltwater more than freshwater fishkeeping, an acclimation box is kind of a must-have accessory. Fish can be rather spicy in their attitudes towards each other; new additions are often best acclimated slowly to prevent excessive stress and so you can make sure they’re eating properly before throwing them into the fray. These containers also come in handy to temporarily separate bullies or their victims.
This acclimation box design features a honeycomb pattern that allows water to flow in an out freely, and gives fish inside and outside the box a limited view of each other. It attaches to the tank rim.
→ Print aquarium acclimation box
Hose connectors
As I’ve said, fishkeeping sometimes feels like it’s all hoses, hoses, and more hoses. The hoses never cooperate, they’re never the right size, and they sure never fit each other the way we’d like to.
Luckily there are loads of prints out there meant specifically to make the endless hose wrangling a bit less frustrating. We’ve already discussed the tube guide, a real lifesaver, but these adjustable hose connectors are also incredibly handy. You can print them in any size, so they always fit.
→ Print aquarium hose connectors
Overflow grid
Aquarium accessories like overflow grids can be surprisingly expensive, which is why simple designs like this one are so perfect to print at home. No trip to the aquarium store needed and no shipping cost included.
With the help of a this protective grid, water from the surface evenly flows into the overflow box and to the sump. Fish and invertebrates do not. What more could we ask for?
→ Print aquarium overflow grid
Light mount
If your tank didn’t come with a light (or you got a kit and aren’t happy with the light that came with it), why not print one yourself instead of spending a pretty penny on fancy aquarium lamps? There are plenty of different aquarium light mount designs out there that allow you to mount cheap LED lights into a free, home-printed fixture.
The mount design printed here is perfect for tanks that don’t need too much light, such as low-tech FOWLR set-ups or those with only low-maintenance corals. For more light-demanding aquariums, you can try a homemade LED bar with a printed base instead.
Bugs & critters
Pest trap
Does an infestation of unwanted pests in your tank often mean you should work on reducing waste and cutting feedings in order to fix the underlying problem? Yes. Does a pest trap help speed up the process of getting rid of excessive bristleworms, snails, and other annoying critters, and is it therefore a fantastic weapon to add to your arsenal? Also yes.
Pop a piece of bait into this pest trap, place it in your tank overnight, and discard the “catch of the day” in the morning. No species of pest can resist an easy snack, and once they crawl through the holes into the trap, they’ll find it almost impossible to get back out.
Pod breeder
Copepods and amphipods are the kind of thing we take for granted in our tanks: self-replicating armies of tiny cleaning agents, indicative of the health of our set-ups. That is, until we get a mandarinfish or other dragonet and discover how valuable those little crustaceans really are.
For dragonet keeping, I recommend printing at least two pod breeders. One can go in the main tank, giving the pods a safe place to hang out without the danger of falling prey to your fish and forming a steady flow of occasional food as they venture out. The other one(s) can go in a dedicated pod breeding set-up, like in your refugium.
Invert hide
Doesn’t matter whether it’s a shrimp, crab, or bright purple reef lobster: inverts gotta molt. When they do, they like to seek out a sheltered spot until their new exoskeleton hardens, helping them to prevent falling prey to hungry fish and overly curious fellow invertebrates.
There are loads of different prints out there for invertebrate caves and hides. I particularly like this four-tubed design, which allows for proper water flow inside. Stick a frag holder with a coral on top and you’ve got the perfect temporary bug home!
Bonus: Sea urchin hats
We’ll close out the list with the most important print of all (in my opinion, anyway). Did you know that many common sea urchins, including the appropriately named collector urchins (Tripneustes, Toxopneustes) and the popular tuxedo urchin (Mespilia globulus), like to pick up items and wear them on their spines? The practice of donning shells, macroalgae, and other debris protects urchins from UV radiation in shallow water. It may also help camouflage them.
The best thing about this? Urchins will pick up anything. That includes tiny 3d printed hats. Is making your sea urchin wear funny hats and helmets practical or productive in any way? Not at all, but it’s absolutely hilarious—please be sure to email us a photo if your urchin decides to don headgear!
Sources & further reading
Ziegenhorn, M. A. (2016). Best dressed test: A study of the covering behavior of the collector urchin Tripneustes gratilla. PLoS One, 11(4), e0153581.
Print design & image credits
