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/The Conscientious Marine Aquarist

Collecting Your Own Marine Organisms

Bob Fenner

How livestock is moved on jets. an LD3

Why would you go to all the trouble and expense to go and get your own marine livestock? Do you dive? Think you might save a dollar? Maybe the adventure! A vacation to get away from the hustle and bustle? Maybe just for the fun and relaxation? Have you ever experienced the thrill of the out of doors, hunting, nature watching, or trying to take pictures? There is another element of being the "great hunter"... collecting marine fishes and invertebrates for marine aquaria.

Like most endeavors, the more you look at live-capture of marines, the more there is to see. Ever wonder why saltwater pet-fish and invertebrates cost so much? You're about to find out. Collecting is hard, yet rewarding work. Let's consider what it takes to "bring 'em back alive" step by step: gear, technique, transportation, planning as well as considerations of the law, conservation and safety.

Tools & Materials:

Hand Nets: <To do: check slide f's, scans for Steve's wonder net pix>

These are your best bet for getting specimens, just like professional collectors. You can make your own hand nets (get some help here) or buy them commercially from sources in the classifieds of aquarium magazines.

The best nets are made with an inner and outer metal hoop with the netting itself hung on the former to prevent chafing. I suggest making or buying two sizes, about six and twelve inches in diameter, with wooden handles that make the overall apparatus float just slightly underwater. Wouldn't a noose with a sliding keeper be handy for securing the nets on your arm and out of the way when not in use? A deep-bodied netting arrangement involves making a long (two to three foot) cylinder of one-half inch monofilament mesh which is virtually transparent underwater. If all you have is white netting it's best to dye it brown or green. To prevent damage to the your intended prey choose the most supple netting material available and keep it out of the sun to keep it soft.

A Poker:

This may be the only other tool you need; it is generally a probe of metal, though some folks use plastic or wood, maybe as part of a hand net handle, to "goose" prey out from one of few escape holes. My favorite poker is a semi-flexible one-eight to three-sixteenths inch diameter copper tube that can be bent to fit around corners. The color contrast makes it easy to see and the bendability gets the poker into hard to reach places.

Barrier Nets:

Are used by collectors in addition to hand nets and a poker. Most commercial divers incorporate barrier or fence nets to increase their catch numbers and range of species. These are an invisible plane of small mesh netting three or four feet high by twenty to fifty feet wide with line of floats at top and lead line at the bottom to keep the net deployed.

The diver surveys a promising area for quarry and bottom contour. The barrier net is arranged to minimize escape along the bottom and sides, broadly into a U-shape to direct or chase prey into. Specimens are caught off this barrier with a hand net.

Other Net-Types:

Before you start dreaming about how you're going to spend all the money to be made by collecting with other kinds of net gear and techniques, let me hasten to remind you that most of your intended prey has to put up with the same limitations of decompression as divers. Some exceptions are hawkfishes and gobies that don't have gas bladders.

Throw nets, push nets, hoop and lift nets, gill and trammel nets, seines of different sorts, among other types of nets are inappropriate technology for the most part, doing too much physical damage to specimens through abrasion and/or rapid ascent.

Seines and trawls generally result in bio-mush; organisms getting so beat up their Dead On Arrival or soon to be. Besides, these other nets are usually unlawful (aka illegal) for collecting; and unnecessary, as you'll see.

Collecting Buckets:

What are you going to do with a specimen after catching it? Unless you're in very shallow water near the shore or a boat, simply dragging it to the surface won't work. You'll want a temporary holding container on the bottom with you. The most popular are plastic bait buckets with a spring door, or if you have a better-mouse-trap idea, some other contraption with a door or removable lid to prevent your catch from escaping. Fit your collection bucket(s) with a snap ring, line and weight for anchoring. The snap hook comes in handy for hanging off the collection receiving buckets from your dive weight belt and the decompression line.

In practice a collecting bucket or two is either hauled around attached to the diver or parked nearby. A little air is blown into the bucket if it is not fitted with a small float; positioning the receiver for easy access and keeping it from getting banged on the bottom.

At the end of collecting at a particular depth the collecting buckets are attached to a securely weighted and tied off decompression line to facilitate bringing slowly to the surface.


Come in several shapes, sizes and varieties. They are especially useful for predatory animals, e.g. morays, basses, and passive "night fishing". Their common element is the use of tunnel like openings (fykes) that allow the catch more in than out. Usually these are baited with something meaty.

Slurp Guns:

Are a "cylinder in a tube" arrangement, sort of like a large hypodermic syringe without the needle, operating in reverse. Most are actuated by hand, but I've seen some doozies that were elastic band, pressurized air and spring powered; very scary above water.

Slurp guns have limitations in terms of practical suction power and maneuverability. A gun might work for you if you're after a single type of small sedentary fish like a goby. Slurp guns are not much used in the "real world" of professional collecting. They have proved too limiting due to nozzle size and mode of execution for fast-moving or larger fishes. Also, compared with hand nets there is too much risk of injury to the prey.

Hook & Line:

Maybe a "reel" possibility (pun intended). Some super-deluxe species like the harlequin tusk fish are harvested this way. Underwater fishing procedure involves filing the barb off a small hook, rigging with an attractive bait, and "jigging" (slowly pulling the line up and down) in front of prospective areas and actual fish. Small hook holes in the mouth heal over in a few days.


There are various drugs, anesthetics and outright poisons used at various places around the world to gather marine life for food, science and the aquarium hobby. They are officially banned almost everywhere and for good reasons. They're toxic to marine life, the environment and humans! Don't even think of using them; they are bad news. Is this clear enough?


If you want to catch a fish, you have to think like one. As aquarists we have vast amounts of specific information of the range and types of behavior of many kinds of aquatic life. Particular species have habitat preferences and evasive maneuvers, varying with their size, sex, and available substrate. You will need to use that data to your advantage.

Where to Collect:

All marine environments offer opportunities, not just the tropics. Nor is serious collecting just able to be done via scuba. "Mere" snorkeling, wading and beach-combing are fruitful. Numerous colorful and exotic fishes and invertebrates may be collected in shallow water. They are also easier to maintain in captivity, being accustomed to greater variations in water temperature, salinity and chemistry.

Capture Know-How:

Time well used go into developing the expertise of intelligent collection. The knowledge and skill of using tools and materials defines the successful collector.

You must know your quarries habits. Some, like many species of surgeon, butterfly and angel fishes can be directly netted after being driven into a barrier net or flushed from undercover. Some wrasses can be chased into diving into the bottom substrate and netted through scooping up and seining the sand through your hand net. Clownfish in anemones, dwarf angels, anglers, frogfishes, hawkfishes and other sedentary types can be challenged "hand to hand". Others require subterfuge; blowing bubbles, shouting underwater, a broken urchin for bait... and practiced eye-hand coordination.

The seasoned hunter knows the flight behavior of their desired species. how do they learn this? By being a good observer principally, and talking with others.

Once in the hand net a quick twist of the wrist, closing the front, will ensure capture; this is why hand nets need to be so "deep". Take care when transferring captured organisms into the collecting bucket. Do not overcrowd or mix incompatible species in the receivers; you'll end up with frayed fins and parts.

I put crabs, shrimp and lobsters each in their own individual plastic, screw-top jar to prevent cannibalism and crushing. Fishes are loaded into the receiver by deftly turning the net inside out while keeping a firm hand on the animal, pushing it on through the bucket door.

Marine life has to avoid predators and currents much stronger and agile than we clumsy humans and can escape in an instant. Watch what you're doing; many fishes can inflict significant damage with gill cover and fin spines, and some like triggerfishes can give a nasty bite! Be wary of venomous organisms, e.g. scorpionfishes and their relatives, sea urchins, fire worms and corals among many others. When and where in doubt, don't touch.

Night Diving:

A time not to be missed. Many day-active organisms can be easily "picked up" by the cover of night. You might be tempted to dispense with a hand net altogether, but I encourage it's use. Triggerfishes can have their second dorsal spine depressed, unlocking their anchoring mechanism for ready removal. Other fishes you'll find "resting" on the bottom in crevices and caves at night, just like in an aquarium.

I carry two small flashlights, one on a lanyard on my free hand forearm and the other on a wrist strap on my net hand. Some folks get along without a light source at all, using just what's available "naturally". There are also really inventive head-mounted arrangements accessible through dive shops.

Scope out the proposed night site at least once during daylight time to familiarize yourself with bottom features and currents.

Time to Go Up; Ascent:

So now after a near-Herculean effort you've finally netted and placed specimens in the collecting bucket and are ready to surface, but what's wrong? Oh no, the fishes are upside down, bloated so much they look like they're going to pop! Guess what? As you know, most of the desired fishes have a swim-bladder, a gas-filled organ utilized to keep the fish at a certain depth without constantly swimming; a hydrostatic mechanism like a diver's buoyant compensator. With time gas is resorbed by the swim-bladder on slow ascents; too fast and there's trouble. Depending on the type of fishes collected at what depths a period of decompression adjustment will be necessary. This is a highly stressful movement as you might guess. Most fishes never come to the surface as adults.

Unless you're collecting in very shallow (skin diving) depths, you'll want to study the tolerances of your intended prey to determine how quickly they can be surfaced. As a rule of thumb, past a capture depth of fifteen feet, we're talking a wait stop of about two meters every fifteen minutes.

There are hypodermic needle gas-bladder "bleeding" and "squeezing" techniques of outgassing for the sophisticated and non-squeamish but let's be real.

At The Surface:

You're not done yet. Once on board the boat or on shore the livestock need to be re-sorted and transferred from the collecting bucket/s to something larger that's waterproof. Standard operating procedure calls for plastic trash cans with double liners, unsealed for the trip back to shore.

Maintain a constant vigil over your catch. An air pump and stone aerator and frequent water changes may be necessary if there is even moderate crowding. Freshly caught livestock often defecate a great deal. If you notice that the air bubbles coalescing at the surface aren't readily bursting, change the water quick.

If you're camping out you can set up temporary live-holding quarters in an underwater cage (be wary of tidal changes); or if you're at a hotel in small tanks, coolers or styro boxes. This is preferable to shipping just-captured specimens. A few days in captivity affords you time for observation and allows the specimens to acclimate to captive conditions.


This is, believe it or not, the biggest problem area; where most wild-caught livestock is lost. Anything collected must be housed while waiting for the long transport, properly packed, rushed to the point of pre-prepared destination, and properly acclimated to their new surroundings.

The Law:

Licensing may be important; there probably are restrictions, at least a tax of some sort to pay for overseeing the resource and to subsidize enforcement against those who haven't paid. Call the state Fish and Game, dive shops, and pet-fish stores in the area for specific information. Permitting should be simple and inexpensive, if allowed, and you should state that it's "for personal consumption" only. That is, not for commercial sale. Make sure this is clear to the licensing agency.


Do you know what you're doing? No? Then don't do it! Don't even touch organisms that are not in your knowledge or experiential realm and collection "game plan". Study up before engaging in that grand collecting expedition. Always shy on the low end in terms of numbers of specimens taken and their size. Smaller individuals generally will adapt easier to captivity.

A note regarding collecting "rock" with or without observable living things in or on it; most times this is a disaster. It will die, smell bad, and in all likelihood turn your tank into bouillabaisse. At least make sure you have accommodations to quarantine "live rock" for a few weeks before putting into a permanent display.

Be careful! Not just what, but how you collect determines the renewability of the reefs' riches. Take pains just like viewing-only diving to disrupt the environment as little as possible. Does it have to be re-stated here? Replace any over-turned rocks to their previous position! Thanks.

Finally, keep a check on the progress of specimens you've caught before hauling or shipping them back. If they're faring poorly, seem dis-interested in their temporary quarters, if fishes have excessive redness along their fins, or visible bruising, release them; they will probably not make the trip.

A fish store might well accommodate your needs for packing and shipping gear and even assist you. You need pet-fish store items like Styrofoam boxes, preferably with cardboard covers, double plastic bags and oxygen. Some intrepid types try to "live haul" their catches without sealing them up . The use of oxygen and light-sealed boxes go a long way to calm down your catch. Though you may be traveling only a short distance this standard method will optimize the arrival quality of your specimens.

At the End Point:

Rapid receiving is of paramount importance. Have your tank(s) set up and ready for the new stock. Acclimate on arrival and put them away. Leave the lights on and skip feeding for a day or two.


Here comes those time worn admonitions: Dive safely!: with a buddy as professional collectors do. Even if you're not working the same site at the same time, it's easier to keep track of your tackle, the boat, anchor, decompression and dive time, etc. and it's much more fun!


 Use close-fitting gloves without cuffs that can get hung up on apparatus or the bottom. I prefer cheap cloth ones as opposed to rubber for greater sensitivity and control. Booties or tennis shoes are mandatory also for obvious foot protection. Ditto for at least something in the way of body cover. A thin to thick "skin" or wetsuit even in the tropics, something for your head, above and below water; to prevent sunburn, coral and other scrapes. You'll thank me; you're welcome.

One last time regarding "picking up strangers". What would your mother say? Don't do it. Assume all invertebrates can sting, fish's bite, urchins spine... And leave them alone accordingly.


Just like any other adventure, collecting is made more enjoyable and fulfilling through careful design. Not only will the expedition go more smoothly, but planning greatly adds to your enjoyment through anticipation.

What do you want to catch? What is there to gather where you're going? What sort of gear will it take to capture it? How about transportation? And once it's home, how will you keep it in good health? Do you need to contact the local "Fish and Game", dive shops, travel agencies? Is it possible to practice with your new tools and hone your netting skills in someone's pool?

If possible, talk with and go collecting with experienced people before investing in equipment or making your own. Contact the large learning institutions and possible public aquaria in your area, or where you're traveling to. Chances are they can put you in contact with people and agencies that do scientific and commercial collecting; very valuable. Some organizations gather troops together expressly for such excursions. A great way to learn the ropes, share experiences and help gather data and specimens for public display.


Few activities are as exciting, educational and humbling as trying to collect wild livestock. Personal observation, photography and bringing 'em back alive enhances and reinforces our appreciation of the living aquatic world and ourselves.

With planning and forethought collecting can make a trip of a lifetime and yield months of aquarium enjoyment.

Bibliography/Further Reading:


Anon. 1990. Supplying the marine aquarist. SeaScope Vol. 7, Summer 1990.

Blasiola, George C. Environmental impart! How we can change aquarium trade practices to achieve long-term environmental benefits. Pet Age 5/92.

Fenner, Bob. 2001. Collecting Your Own Marine Organisms With An Emphasis on Diving. FAMA 4/01.

Goldstein, R.J. 1990. Deep reefs, the mid-Atlantic waters could become an important source for marine tropical fish. Pet Age, June 1990.

Havekotte, Tom. 1984. Collect marine life without drugs. FAMA 6/84.

Kattman, Dianne L. 1982. Collecting your own. FAMA 12/82.

Kenney, William R. 1988. Collecting tropical marines in New England. FAMA 11/88.

Parker, N.J. 1976. Night time collecting. Marine Aquarist 7(5), 1976.

Piednoir, M.P & C. 1994. Fish collecting in the Maldives. TFH 10/94.

Randall, Jack. 1971. Collecting small fishes. Marine Aquarist 2(3) 1971.

Sammon, Rick. 1989. The challenge of collecting marine animals. TFH 2/89.

Schlais, James F. Collecting... for fun, dollars and pesos. FAMA 1,2/80.

Schlais, James F. SeaVac SVXL; marine specimen collector (product test). FAMA 1/82.

Siri, Paul & Colin Barnettt. From reef to retailer, the collection of marine aquarium fish. FAMA 9-12, 1980.



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