Introduction: Build an Artificial Reef

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Some reefs are erroneously constructed from car tires (a bad idea due to the toxicity of rubber disintegrating in salt water), and some are built using broken-down cars, old boats and scrap metal.  Our goal was to ensure that fish and other marine animals, such as crabs, octopus, and eels, looking for a place to live and reproduce had the best environment available.  The reef project chose cinder block because the block was much easier to handle than cars and other heavy industrial items and the Calcium content of concrete bolsters the growth of various plant and invertebrate life forms.  Also, logistically it made more sense because block is readily available.  The fish habitats are formed into an “igloo” and “caterpillar” shapes  which offer the best environment to live, breed and find protection. 

Step 1: Choose Location

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The very first step is to choose a low current location that is conducive to undersea life, reproduction and feeding.

In 1985, a 60-foot tuna-fishing vessel of Mexican origin was anchored close to the beach in Playa Hermosa. A fire broke out aboard causing considerable damage and the boat sank. In 2002, fishermen living in Playa Hermosa knew the location of boat and helped discover the wreck and the remains of the fishing vessel. The wreck has a N-S direction. To the south is a drum with nets and ropes completely covered with vegetation and corals, at the center is the engine and various mechanical parts of the arms. At the other end, the north, one can see a metal cube of about 100 cubic feet that is most likely a fuel tank. The wreck lies about 400 meters west from the beach, facing the parking lot of the first entrance to Playa Hermosa. It sits at a depth roughly 20 to 30 feet depending on the tide. 12 fish habitats consisting of the igloo block structure are located around the wreck..

While the CondoFish project in Playa Hermosa Costa Rica obtained full government approval for the project, this may or may not be relevant in other international locations. Costa Rica is a very ecologically conscious country and anything regarding natural resources or wildlife requires approval and constant surveillance.

Step 2: Test Reef Design Outside of Water

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While you may have a good idea of what your design will be.  We highly suggest testing your design outside of the water.  This will save valuable building time underwater. 

The following steps will show the design that the Playa Hermosa Artificial Reef Project used.  It seems to be good design to start with.  After a 3 month period, an explosion of aquatic life has occured in the in and around our "fish condos".

Step 3: Move Materials to Site

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Move your materials to your building site.  We chose a clean patch of ocean floor and dropped the cinder blocks one by one.  Then we built the Reef structures by moving the blocks from the pile to the building site. 

Step 4: Build Your Base

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Build your base on level sea floor.  Anchoring should not be needed if the location chosen is calm enough.

Step 5: Add Levels 2, 3, and 4

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Build the sides up to the 4rd level.

Step 6: Add the 5th Level and the Center Support

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Add the 5th level and the center support.  The 2nd image is a cutaway shot to show a better view of the center support.

Step 7: Monitor, Maintain and Protect

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Now, monitor maintain and protect.  We make weekly visits to the site and constantly think of way to make things better.  Pending approval, we'll be building more structures and requiring more and more support.

Step 8: Progress Pictures After 1 Year

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It's been nearly a year since we dropped the first blocks in the water.  What was once a bare sand bottom, is now teaming with life.  The blocks are covered with calcium based creature, soft corals, crabs, fish eggs and school of fish frequent the area.  Add to the that the life in the Benthic zone under and around the structures is doing very well.  


scubaru (author)2010-08-04

This is awesome, I am a certified scuba diver (PADI) and would love to do this in a local river nearby.

SurvivalGardener (author)scubaru2010-08-04

You should come down and dive the Reef!

blkhawk (author)2010-07-25

Great job! Thank you for helping the environment.

Wasagi (author)2010-07-24

This is amazing!

yokozuna (author)2010-07-24

Fantastic, five stars.

Skai (author)2010-07-24

oh the beautiful fish on your site! they must be so happy! awesome job :) say, what do you think about putting something like this in an artificial pond in New England? just wondering

Michaelgoode (author)2010-07-23

Nice job guys, lets just say theres some people who care about the planet. To says its that easy and cheap to make a home for many, absolutely brilliant, well done :) :)

canida (author)2010-07-23

This is excellent! I'd love to follow the time course in photos as fish colonize your artificial reef. Will they be posted on your site?

SurvivalGardener (author)canida2010-07-23

Yes, the adrian stacey gallery is right after we got the fish condos built. The gallery is the most recent we have some new pics and a video that should be going up in the next day or so. I'll continue to add photos for 2010, then make one for 2011.

VanillaXtiffy (author)2010-07-23

This is awesome! Anything to help fish has my support!

Well, anytime you want to come dive it, you're welcome. And donations are accepted via our website via a Paypal link on the sidebar of our site. Thanks for your support! And come check out the site and look around. Thad

mannyorts (author)2017-10-14


Faith2 (author)2017-02-17

This is amazing, can I build it higher like high enough to see above the sea level or is that impossible :D

Bigtimefish (author)2016-04-18

Beautiful job! I'd like to try this off Ocean City, MD.

ZiyadT (author)2016-02-29

Very nice idea ! Good luck to everyone

masoon (author)2015-02-22

This is so cool, please put some more pics of this as it grows.

josuchav (author)2014-11-28

Are you extracting those tiger fish? I saw a picture that looks like you have one in there.

jimwi (author)2013-09-16

Have you got any update pics. Would love to see how the reef is going.

astral_mage (author)2013-09-16

have u thought of doing a under water type of camera tethered to a small buoy thats set up 4 solar charging an wifi?

Excellent idea! No we haven't. But I'll consider that on the next project like this. I'm not sure how long it would last though. If stuff isn't tied down or locked to'll get taken. The project is on it's own now but still a fun local spot to view an abundant amount of marine life.

thepelton (author)2011-05-10

I'm glad you did that "One year later" shot. Did I give you the idea?

Was that you? Then yes......I remember someone asking for it.......

Pura Vida

De Nada. Buena Suerte.

pdasarathan (author)2011-12-01

cool nice work .. its also cheep

thingy (author)2011-08-03

How much do you charge for rent? The area looks nice and i'd love to be in a condo. I hate cutting my seaweed lawn.


Bob the Pistol Shrimp

ytashi (author)2011-08-02

ok now i'm definately going to raise funds and contact our local fisheries and environmental department to organise this.. <3 swing by malaysia to scuba dive n enjoy nature at its best guys!

SurvivalGardener (author)2011-05-15

They've become more more common in the Condofish project. Hadn't seen them at all until a few months ago. They are cute!

build52 (author)2011-05-15

I love the squid he's so cute.

tubbles (author)2011-05-15

A lot of reef building/preservation projects encouraging coral growth use certain types of wire mesh. As I understand it, polyps and algae etc get caught on it, then it builds up over time and eventually forms the beginnings of a reef. It allows reasonable freedom over shape and other factors, and is good to get tourist funding. I think DAN did an article a while back.

Bear in mind, this probably only applies to the faster-growing types of coral.

PADI rescue diver, BSAC sports diver

jlumagod (author)2011-03-26

hello condofish please allow me to ask for your email add?

Please visit our website. It's in the contact section.

jlumagod (author)2011-03-26

wow its really amazing.... i like it very much.. :) more fish will be survived with your idea... really

kibukun (author)2010-08-18

Oh sure toss them in and scare the fish off why don't ya?

SurvivalGardener (author)kibukun2010-08-18

You'd eat your words if you dove down with us and saw all the fish and the new growth since we "tossed" those bricks in. Pura Vida

kibukun (author)SurvivalGardener2010-08-20

I know I was just going to suggest a small crane or scuba vehicle to hoist them in. You might get the fish to move in earlier. Also it's good if you're setting it down in a tight spot where you can't toss them in or they'll roll/ slide of the slope you're setting it on. I believe fish mostly like cliff sides (underwater cliffs of course) don't they?

SurvivalGardener (author)kibukun2010-08-20

We have 12 structures built and not enough money for a crane or even where to find one around here. The project is not on a slope and so far so good. Thanks

kibukun (author)SurvivalGardener2010-08-22

I'm sorry, you didn't get what I meant... I mean like a small winch that you can build on the boat. The Instructable way!

SurvivalGardener (author)kibukun2010-08-23

Sure you could, but then you'll have to move all the blocks along the sea floor during construction which might defeat the purpose of being so careful in the original drop. Plus, they don't drop that fast once they're in the water anyway. Back to the original point of scaring away the you think is would be better to put all of the block down there using a more time intensive winch process, or all at once over a period of only 10-15min.

kibukun (author)SurvivalGardener2010-08-24

Well, actually if you use a double winch routine you can get all or half the blocks down there all at the same time. Cutting the time from an hour of hand moving them to just lowering all these blocks in half the time. I think you also might be able to lower it already built. Making less time. I'd propose a catamaran double winch setup lowering a plywood platform that you can lower down the blocks with.

SurvivalGardener (author)kibukun2010-08-24

Not trying to be difficult, but I don't see the advantage over just dropping them in on a bare seafloor?

kibukun (author)SurvivalGardener2010-09-07

just suggesting a more quicker way in case you'd ever need it.

explosivemaker (author)2010-07-26

very cool...may not apply to the majority of people, but nice to see....that picture with a fishy enjoying the new house is neat

That's Renny the Pufferfish. Check out more pics of him and his intersting life story @ haha

wow, even more cool pictures...thumbs up to the photographer(s)

Zaidron (author)2010-07-26

Hi, I really like that COFI logo, Could you please tell me the fonts names? thank, Zaidon

DreZaz (author)Zaidron2010-07-28

Hi Zaidron, I designed the logo of the condo fish, I am glad that you like it. The name of the fonts I have used are: Bellerose Light:1.0 for the Cofi and for the small script it is Bradley Hand ITC TT Bold. If you need any design work done, you can visit our webpage:

handyman29 (author)2010-07-27

Hello reefmaker, I heard that you can speed up the growth of coral reef by sending an electric current through artificial reefs (conductive/metal ones of course). I am planning to test it myself one day. From what I watched, coral began developing on about one week depending on the voltage you send through the reef. Just something to think about.

SinAmos (author)2010-07-23

Ummm. I don't think this is going to make waves break nice.

SurvivalGardener (author)SinAmos2010-07-23

Sorry. This is not a reef for surfing. Its 30 feets down and for increasing aquatic life in the general area. We have 12 of these igloos down there. And it's working!

SinAmos (author)SurvivalGardener2010-07-23

Yeah, but it also isn't doing the job a reef does, which is aerating the local waters, creating breaks that let oxygen fuel the life unlike dead zones. Bio-mimicry is your best bet, but I'm just letting u know. It is a nice attempt, but manmade blocks just doesn't fit the environmental requirements as much as man would like to believe. Sure, u create a home, but the water isn't rejuvenated with oxygen, which is what we want along the cost. That is the point of nice breaks.:)

About This Instructable




Bio: I hang out in Costa Rica and build fun sustainable, eco, survival related projects.....My main goal is to be able to feed the family ... More »
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