Introduction: DIY Zookeepr / Lionfish Containment Unit

Lionfish are an invasive fish in our waters (Caribbean, entire Gulf of Mexico up as far as Washington and they’ve been spotted in the (Atlantic-side of) Brazil waters) and are the only ones allowed to spear on my island. Harpooning is illegal here. Fishing is a different story.

Although beautiful, if we let them “do their thing”, that means the end of a healthy reef in waters where there are no natural predators.

Map of the native range of Pterois volitans (green) and Pterois miles (blue) adapted from Schultz (1986) and Randall (2005). The star in the Mediterranean Sea denotes Lessepsian migration of P. miles via the Suez Canal (Golani and Sonin 1992). Non-native range of P. volitans and P. miles in the Americas is shown in red (from Schofield et al. 2012). Predicted future distribution of lionfish along coastal South America is shown in red hatching (from Morris and Whitfield 2009) source;

In order to combat the still growing Lionfish population I’m offering my design to a “lionfish containment unit”. This is my go-to zookeeper given any choice! Compared to ‘the original zookeeper’ this design is lighter, cheaper, faster draining, customizable and up for personalization! The model explained in this instructable and features a window, speartube, holding handle and custom draining system. Because models on the market these days are too expensive and don’t offer enough customization for lionfish-hunters and other divers. That’s why I decided to make my own!

I’m a scuba instructor and underwater technician.

This is my first instructable so plz bear with me… and if you catch me on any typo’s, spelling or other language-related-mistakes, my apologies in advance, English is not my primary language!

another appology for the big picture sizes, i tried messing around with them but didn't work properly, so i left them quite big...

I’ve cut the containment-unit-build-up into 8 steps; tools and materials, draining system, tube, window, speartube, coupling, funnel and finishing up. There are also a bunch of alternatives listed at the end.

Time of construction:

Optimal; 2,5hours
Realistic; 4-6hours

Step 1: Tools and Hardware

At the beginning of each segment I’ll put up a list for that specific part.

(ALT) means there is an alternative way, method, tool or material that can be used. Described in the last section.

Here is a complete list of tools and materials needed;

Zookeeper materials;

  • 48x aluminum 3/8” (less then 0.5inch) rivets 8/32
  • Fancy stainless steel handle (drawer-, closet- or cabinethandle) incl. nuts (ALT)
  • 4x stainless steel 1” bolts 8/32
  • 2x stainless steel ½” bolts 8/32
  • 6x stainless steel lock nuts 8/32
  • 4x ½” spacers (ALT)
  • 1m (3’) paracord or other kind of rope
  • 1 clip/ carabiner (ALT)
  • 1 sturdy/ heavy duty funnel (160mm)
  • [Specific length of] 160mm PVC plumbing pipe
  • [Specific length of] 50mm PVC plumbing pipe
  • 160mm PVC plumbing coupling
  • 160mm PVC plumbing endcap
  • 160mm PVC plumbing screwcap-coupling
  • A4 size laminating pouch (125micron) (ALT)
  • Small logo or picture (optional)


  • Electric drill
  • Drill bits; 11/64 (specific to rivet-size) + 7/64” (not specific, needs to be small)
  • Jigsaw (optional but highly recommended) (ALT)
  • Soldering gun (optional but highly recommended) (ALT)
  • Laminator (ALT)
  • Riveting gun
  • Miter box (optinal but recommended) and saw
  • Pvc cement (Waterproof, that stuff you use for plumbing pipes)(ALT)
  • Small bahco (adjustable wrench)(ALT)
  • Small screwdriver(ALT)
  • Stanley knife / exacto blade
  • 50mm hole saw (optional but recommended)(ALT)
  • Stovetop/ heatgun/ source of heat (optional, not recommended)(ALT)
  • Sanding paper (120-180 grit)
  • Permanent marker/ sharpy
  • Couple rubber bands
  • Measuring tape and ruler

Material cost and where to get:

This one is mainly for my island people in the Caribbean, specifically Curaçao. On islands everything is always more expensive and harder to find, so for Americans and Europeans it will probably be cheaper.

  • I get my 160mm PVC plumbing pipe; by the meter @ martina plumbing (+- nafl. 18,-).
  • Get all the rest of your PVC parts @ Kooijman (+- nafl. 35,-)
    I also get my 50mm tube, SS bolts and handle @ kooijman (+- nafl. 20,-).
  • Rivets are best bought at CFT (CuracaoToolsandFasteners) nafl. 12.50 for 100 aluminum rivets.
  • I get my funnels @ Satex and for a measly nafl. 2,50 a pop!
    For a custom size funnel, I use the sturdy black oil-funnels from kooijman or napa (nafl. 4,-),

Making the total cost around nafl. 75,- to 85,-, compared to at least nafl. 200,- you pay at the store.
For the curious; 1$ goes for 1,75 nafls (so total cost would be around US$50,-)

Step 2: Draining System

Tools and hardware;

  • Electric drill + both drillbits
  • Jigsaw
  • Small bahco
  • Screwdriver
  • 50mm hole saw (optional but recommended)
  • 160mm endcap
  • 160mm screwcap-coupling
  • 4x stainless steel 1” bolts 8/32
  • 4x stainless steel lock nuts 8/32
  • 4x ½” spacers
  • Sanding paper (120-180 grit)
  • Permanent marker
  • Ruler

We’ll start off by building the draining system and endcap to the container.

Grab the screwcap-fitting (from the top-section), unscrew cap, remove rubber ring.

Take your electric drill and the small 7/64” drillbit and put 3 holes, as close to eachother as possible, along the rim of the cap. Poke through the leftover plastic so you can fit your jigsawblade through. Carefully cut the complete circle inside the rim out, do this neatly, we need both pieces for construction!

Sand down any rough edges on both PVC pieces.

Put the rubber ring back in the rim and re-screw onto screwcap-coupling. Put aside for now.

My endcap is divided into 4 segments already which would make it easy for me to find the centerpoints where I need to drill, yet I use the cut-out and my template to find and drill the first holes.

I have a simple but handy draw-out on paper which helps me find exact positions for this. As the pictures show, I use the draw-out to find the center, put a big cross on it (connecting 4 equally spaced dots) and measure about 1cm back from the edge. Drill these out, flip it over and use the holes in the cut-out as a template for hole positioning in the endcap. You can draw dots through the holes or drill directly though into the endcap. This helps with lining up all the holes!

Using the 50mm holesaw we need to put a big hole in the endcap. Yes, in the middle! Save the small cut-out! We’ll use it later on for the speartube!

Now put the 1” bolts through the lid, spacers in between, and the cut-out on top (use your marking for easy alignment) and using 4 locknuts locking the endcap/ draining system together.

Step 3: Tube

Tools and hardware;

  • [Specific length of] 160mm PVC plumbing pipe
  • [Specific length of] 50mm PVC plumbing pipe
  • Miter box and saw
  • Sanding paper (120-180 grit)

I always start out with measuring out my preferred lengths of tube and using a miter box making sure I get straight cuts (clean up edges after cutting). The pipe is 160mm in diameter and the length is totally up to you.

My width measurements are all based on the funnel; I found a very sturdy kitchen-funnel which fits exactly in a 160mm plumbing pvc tube, so that decided the width. If you have a bigger funnel which fits exactly in a slightly larger diameter pipe, then use it! Funnels are always the first thing to break when frequently lionfishing. Less messing with the funnel means it stays stronger.

I don’t advise going smaller in diameter as the BIG lionfish are already a struggle to get in. The one in this instructable is a small one, only 45cm (17,5”). The end product will be about 65cm (26”) which is good for about 6.5 – 7kg of lionfish (up to 8 if jampacked!). The speartube can be cut shorter, mine is 33cm (13”).

placement is something to consider before you start cutting and drilling. Main question being; “are you right or left handed?”. I’m shooting my spear with my right hand, so I want my window positioned on the left side. Otherwise the window would be facing inwards and not show to other divers along with me.

It wouldn’t make sense placing my handle on the inside, I would have to reach into weird ways to be able to grab that handle. On the bottom wouldn’t make sense either, obviously.

I also like to have my speartube straight under my window (I usually bring a small second spear in case I nick a fish in the fin, then I’ll grab that small second spear and plow it into them devilfish!).

All the items and holes depend on where your window is cut out, so we'll start with this one.

Step 4: Window

Tools and hardware;

  • Electric drill + both drillbits
  • Jigsaw
  • Soldering gun
  • Laminator + pouch + small picture
  • Riveting gun + your 48 aluminum rivets
  • [Specific length of] 160mm PVC plumbing pipe
  • Measuring tape and ruler
  • Permanent marker/ sharpy
  • A4 format paper
  • Sanding paper (120-180 grit)
  • Stanley knife / exacto blade
  • Couple rubber bands

I have a laminated template for all my holes and window cut-out. Here is a quick way of making one;

Grab yourself an A4 paper and draw lines 1cm (3/8”) away from the edges and another one 2cm (¾”) away from the edges.

Round off the corners (if you like) from both lines drawn. On the outer line measure out 48 holes equally divided (take the middlepoint of your outer line; measuring paper from end to end, mine is 29,7cm (just shy of 11¾“) so half is 14,85cm (just over 5¾”)). Mark and use this centerpoint, working your way outwards putting a dot every 2cm (¾”) up to the 12cm (5”) mark. Use this same method for the sides. When top, bottom, left and right are dotted, place a last dot in every corner in between the most outer dots. I got 13 on the top and bottom line, 9 on the left and right side and 4 additional dots in the corners making a total of 48 dots. Don’t go any less! It makes the spacing between rivets bigger, potentially leaving room for a lionfish-spine to stick through!

Poke through your dots with something pointy (small hole only! Use a dart or small nail).

Use this as a template for putting all hole markings onto your tube. I usually put my template centered on the tube in between coupling and the bottom piece securing it with some rubber band to keep it from slipping.

When all the dots are transferred to your tube (which will become the rivetholes), you can cut the outer rim off, following your inner drawn line. The leftover rectangle is the template for the actual window cut-out. So center this again inside all the dots on your tube and trace the rectangle with your sharpie to put that line on the tube too!

We can finally start cutting and drilling! I advise to start cutting the window first. Take your electric drill and the small 7/64” drillbit and put 3 holes, as close to eachother as possible, along the drawn line. Poke through the leftover plastic so you can fit your jigsawblade through. Carefully cut the complete rectangle leaving a big hole in your tube.

Clean up the rough edges with sanding paper.

You can now also drill through all dots around the window hole using the 11/64 drillbit.

I’m using a laminator, so I can incorporate a small personal logo. The 125micron thickness is very sturdy but I also have successfully built it with 80micron which held up fine as well.

You can use the paper cut-out from the window to find the right positioning for your logo or picture (put it under the pouch and your logo inside the pouch in the corner). Now run it through the laminator creating your window!

While positioning it over the window cut-out and securing it with rubber bands my soldering iron is already warming up. I always melt the holes through because it makes a stronger edge inside the hole. Do this in a well-ventilated area, preferably outside! Work from one side to the other and put a rivet in right after melting through your hole to keep your laminate in place. Be sure to wipe the excess plastic off of your solderingtip after every couple of holes!

Hopeyou have a strong forearm, this will take some strength! Squeeze that rivetgun away!

Step 5: Speartube

Tools and hardware;

  • [Specific length of] 50mm PVC plumbing pipe
  • Electric drill + drillbit; 11/64
  • Small bahco
  • Screwdriver
  • 2x stainless steel ½” bolts 8/32
  • 2x stainless steel lock nuts 8/32
  • 50mm cut-out (from bottom segment)
  • Heat source
  • Permanent marker/ sharpy

Okay I got a little trick for this. You could just put a small endcap on the speartube, maybe sand it down flat so you have a straight connection with the tube and be done with it. Ahh a bit of PVC cement for good measure! Drill a reasonable hole in the middle, bolt it on the tube, et voila! The easier and faster way! (so maybe recommended) BUT…

Remember the 50mm plastic disk I told you to save (from the draining-endcap)? With a little heat and a piece of rope we’ll re-use this little disk to a little ‘tube-plug’!

Start off by cleaning up all the rough edges with a sharp knife or sanding paper. You can trim the disk down a little, but it needs to stay bigger as the opening of your speartube.

Now slowly warm up the bottom 5cm (2”)of your speartube above a stove or another way of controlled fire. If you have a heatgun use it! But I think the majority will be using some kind of controlled fire.

Don’t blacken the end, keep rotating and moving the tube in and out of the heat (so hold it ABOVE the fire, not IN the fire). It just needs to soften up, it doesn’t need to melt! Don’t joke around with plastics and fire! Use a well-ventilated area, preferably outside!

When the end is softened up, put your disk on top pushing one side in. Using a pen or anything else but your finger, gently push the disk in and straighten it out. I suggest wearing a glove holding the tube just below the softened part (this way your hand works as an improvised stop for pushing in the disk to far), working in the disk with the other hand.

Remember to leave enough room at the bottom to put a bolt through! 2cm (less then an inch) is enough. When happy with the placement I suggest pinching together the bottom part, below the disk. Now the disk is in there solid!

You can put a piece of rope through the hole with a knot. This way if the disk gets stuck sideways, and you can’t grab it, you can pull it out using the rope!

Note the in the video i put the rope in the wrong way... the cap goes into the into the softened part with the knot going in first, so you could actually pull the disk out if necessary!

Drill2 holes, one on the top and one at the bottom (below the inserted disk) of the tube.

Stick the ½” bolts through the holes and lay it down on your tube (I’m using the print on the tube as alignment). Mark the places the bolts poke out onto the tube, drill and fasten the 2 ½” bolts with locknuts.

Thinking back about “placement”, I’m connecting the speartube about 3cm (1¼”) below the rivet-row from the window. This way when you lay your zookeeper down, the weight makes it roll towards and against the speartube making your window (and catch) visible from above!

Step 6: Coupling

Tools and hardware;

  • [Specific length of] 160mm PVC plumbing pipe
  • [Specific length of] 50mm PVC plumbing pipe
  • 160mm PVC plumbing coupling
  • 160mm PVC plumbing screwcap-coupling
  • Pvc cement
  • Couple rubber bands

Alright, onto how I glue the couplings in; I don’t push them in all the way, giving me about 10-15cm (4-6”) extra height without losing too much strength.

I’m using a rubber band to border off the distance I want connected. I glue both sides with PVC cement and push them onto each other until I reach the rubber band. The rubber band also prevents it from sagging any further down while the glue sets. After a couple minutes remove your rubber band so you can keep re-using them (PVC cement is very quick to set) and put it aside. Leave to dry so we can get to work on making the funnel!

Step 7: Funnel

Tools and hardware;

  • Electric drill + drillbit; 7/64
  • Soldering gun
  • Sturdy/ heavy duty funnel
  • Ruler
  • Permanent marker/ sharpy
  • Stanley knife / exacto blade

Like I said before, this funnel (and its exact fitting in a 160mm screwcap coupling) is the reason for the dimensions of this zookeeper. If you can’t find an exact fitting funnel-screwcapcoupling-combination you can use a bigger funnel and cut it to size, this works fine but is less sturdy as an exact fitting one. The black (oil) funnel in the picture is one that is cut to size.

First off, I saw off about half of the bottom part of the funnel. I’m also using a template in order to get the 8 holes needed in the right position. Marking a ring about 1 below the upstanding rim and using my template to divide the funnel into 8 equal parts.

I drill these using the 7/64” drillbit and use the soldering iron to just tap all holes on both sides (you could also push your solder through, making the hole a little bigger). This makes a reinforced edge around the hole. Using a ruler I put lines from holes towards the narrower part of the funnel.

Now put your funnel us-side-down and with an exacto blade cut the diagonal parts first leaving the narrow part for last. Cut towards the holes following the lines but be oh so careful you don’t accidentally, force your blade into the drilled and molten hole! Carefully cut into the hole following your drawn line not cutting anywhere else in the hole! I actually stop before I reach the hole and gently push it through when I passed 3 or 4 times.

Don’t force your blade through on the first pass, score it first so when you pass your blade a second and third time it has a path to follow.

When you have 8 slots in your funnel, turn it around again and sit down, place the funnel in your lap more towards your knees instead of your crouch, holding onto it. Carefully cut the narrowest part of the funnel, from middle to bottom, following your drawn lines. Again, don’t force your blade through on the first pass, score it first so when you pass your blade a second and third time it has a path to follow.

BE CAREFUL! You might want to put a sturdy cloth or patch on your lap for protection!

Step 8: Finishing Up

Tools and hardware;

  • Electric drill + drillbit; 11/64
  • Fancy stainless steel handle (drawer-, closet- or cabinethandle) incl. screws
  • Permanent marker/ sharpy
  • 1m (3’) paracord or other kind of rope
  • 1 clip/ carabiner
  • PVC cement (Waterproof, that stuff you use for plumbing pipes)
  • Screwdriver

Time to put this baby together!

Starting of with the handle. Mine is placed onto the coupling about ¼ part down compared to the window. Draw and drill your holes and screw handle on!

The rope (paracord 550) goes in line with the top row of rivets. One side connected just above the coupling and the other just above the bottom rim. Just drill 2 holes neatly aligned, pass your cord through and tie a big enough knot so it doesn’t slip back out, even with substantial weight. A simple figure-eight knot is enough in my case. Don’t forget to connect your (closed ring) clip/ carabiner!

Now is the time to glue on the bottom part, no specific orientation, just push on all the way!

Place in your funnel, check the screw-able ring if the rubber ring is in and screw it on!

You, my kind sir or madame, are almost ready to go lionfishing!
Look out for my next instructable making your “DIY polespear”!

Step 9: Alternatives

· No laminator; grab yourself a BIG sodabottle (>3L), cut the top and bottom off and cut the big plastic ring open so your left with a big, sturdy, clear piece of plastic to use as a window.

If your using a big soda bottle you might need to adjust the size of your paper and the number of holes (smaller window means less holes and rivets, bigger means more). Plz keep the spacing between rivets “as close to each other as possible”, at least don’t go wider as the 2cm (¾”) used in this instructable!

· No jigsaw; drill a quadrillion holes! All along the lines, as close to eachother as possible and poke through the left-over plastic using a knife (or anything really). You’ll have a lot of rough edges to clean up tho…

You can also use a figure-saw for the screwcap-cut-out.

Use a close quarter hack saw for the window-cut-out, put the 3 holes in line and fit a hacksaw in. you’ll have to drill holes on all 4 lines of your rectangle since using this way you probably can’t get rounded corners, but those are purely esthetic anyway!

· No holesaw; If you don’t have a holesaw you can use the biggest drill you have and drill lots of holes in between your fastening bolts, try putting in at least 12 or so. Divide them nicely and be sure not to get to close to your screwholes, I’d leave at least 2cm or so (an inch) in between. For the cut-out see alternative for 'speartubecap'.

· No soldering gun; hold a nail (using isolated pliers) into an open flame, heat it up and melt away!

· No PVC glue; I used to use miniscrews and jamming techniques in order for all components to be changed or replaced. When using miniscrews, do check on the inside of your tube if they are not poking through too much, I tend to file them down and flat.

You can also use a (thicker than paracord) rope and jam all tube segments together with this rope in between, you’ll be surprised how well this holds! Push in as far as possible.

· Heat sources; preferably use fitting endcap for the speartube to skip this heatingstep altogether. But using scraps means less trash and less costs!

Use a portable camp stove, heatgun, kitchenstove, gel-based contained fires, alcohol stove etc.

· Nicer-finish screws; I usually use these screw-into-eachother type screws. They leave a very smooth finish inside your tube! A bit more expensive tho.

· Bringing a second spear; I have different length extra spears to exchange on my different length zookeepers. I normally strap a piece of strechcord/ shockcord around the neck of my tube. If your spear is longer than your zookeeper you can use a bungeecord; drill a small hole through the top of the speartube (close to the tube), hook and cringe the hook. You might also have to drill a small hole in the top of your spear.

· Same diameter funnel, bigger tube; use a connector cuff (diameterreductor).

· Bigger tube; If you go up to 200mm most lobster will fit too! Make sure you have a funnel that big!

· Cheaper and bigger handle; often use a gardenhose filled with thick nylon rope as a handle on my own zookeeper. For a 30cm handle, cut 60cm of thick rope. Take a thin, strong rope and tie it halfway around the thick rope, guide the thin rope through the gardenhose, create a hold-on and pull the thick rope (doubled) through the gardenhose. Drill (and melt through) the ends for screws to pass through. It holds way easier, under and above water!

· Clips; lots of options!

· Fixed clips position (or closed ring clips); double the rope and feed it through the opening of your clip, now feed your clip through the loop you just created. This works very well when diving.

· Speartube cap; preferably use fitting endcap for the speartube to skip the heatingstep altogether. But using scraps means less trash and less costs!

lots of plastic alternatives. Some bottlecaps fit, or other kind of lids. Otherwise cut a disk from a bucketlid using a Stanley-knife.

· Screwdrivers; a small screwdriver (needs to fit inside the tube) can even be a loose screwbit.

· Small Bahco; for locking the nuts onto your bolts you also have multiple options. Pliers is only for grip, tighten with other side (screwdriver-side).

· Spacers; I use storebought nylon spacers, but you can use things like wallplugs, stacked nuts, stacked washers, electrical pipe (the yellow one), small blocks of wood with a hole drilled through, even the cut-offs from the funnel will do! I’ve also used the caps from bugspray bottles, copper pipe connectors, rubber furniture feet, steel spacers etc.

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