Cyanide and Its Unfortunate Use in the Marine Ornamental Industry by Steven Pro

For those aquarists who don't know, the use of cyanide to collect animals has been a long standing problem in the marine ornamentals trade. Cyanide has been used for several decades as an "anaesthetic" to knock out fishes and facilitate their capture. The origins of this practice have been debated; it either began in Taiwan in the late 50's or in the Philippines in the early 60's ( When it began, however, is of little concern. What is disturbing is that even though its use was first brought into question in the 70's, it is still being used commonly in some parts of the world today.

I used the word "anaesthetic" in quotes because cyanide is not a true anaesthetic. The word anaesthetic has its roots in Greek, an meaning without and aesthetos meaning perceptible or able to feel pain ( In contrast, cyanide is best described as an asphyxiant (Bellwood, 1981b and Jones & Steven, 1997). It works by depleting the cells of oxygen, basically suffocating the fish until they pass out.

What I also found disturbing in preparation for this article is how little is actually known regarding the long-term effects of cyanide exposure in fishes that initially survive this collection method. And, that the story that I had consistently heard, namely that some fishes do survive the initial dosage but that they suffer irreversible damage to their gastro-intestinal tract and subsequently die of starvation because they are unable to assimilate the food, is untrue. The basis of this aquarium myth comes from a 1981 article by David Bellwood. But, as you will see, there are some problems with this experiment, and he later refutes his earlier work in a paper he co-authored in 1995.

Studies on Cyanide's Effects on Marine Ornamental Fishes:

Bellwood (1981a):

This article detailing early controlled experiments with cyanide-exposed fish discusses common Domino damsels (Dascyllus trimaculatus) that had been exposed to cyanide. These particular specimens had been obtained from a net collector in East Africa, where cyanide use had not been reported. The experimental fish were treated with a sodium cyanide solution of either 1 or 5 ppm. The fish were held in cyanide-dosed water until "anaesthetized" and then kept in the solution for an additional 20 to 30 seconds to be sure the anesthetic effect was complete. It took anywhere from two to three minutes to knock out the fish, with the 5 ppm concentration acting more quickly than the 1 ppm solution. Apparent recovery took anywhere from six minutes at the 1 ppm dosage to 17 minutes at the 5 ppm treatment.

Both the experimental and control group were observed to eat the day following the treatment. Additionally, there was no discernible difference in the external appearance of exposed versus unexposed fishes in this experiment. But, upon further examinations during necropsies, the cyanide exposed fish were shown to have intestinal and stomach damage that the untreated control group did not have; specifically, the exposed fish suffered from a sloughing of the inner gut lining (gastric mucosa). Additionally, in the anterior intestine, the mucosal folds had decreased in size. It is this damage that has led to the belief that cyanide caught fish may feed normally, but are incapable of digesting their food. They are, therefore, thought to slowly starve to death over time.

The problem with this article is that it does not list the number of fish in either the experimental or control groups nor does it offer any statistical analysis of whether the differences noted were significant. Some authors (Goldstein, 1982) have speculated that this maybe the product of overzealous editing on the part of the magazine. Or, it could also be that the author felt that a statistical analysis was beyond what was necessary for a hobbyist magazine. Regardless of the reasoning for the omission, though, it still brings into question the validity of the author's conclusions.

Bellwood (1981b):

In a subsequent article, Bellwood investigated where cyanide might accumulate in the fishes' body other than the gastrointestinal tract, and what effects the drug might cause. Three test fish (called Pomacentrus violascens at the time but now reclassified as Neopomacentrus violascens) were subjected to a 1.84 ppm solution of potassium cyanide. This particular compound is an intentionally radioactive form of the drug C-14 potassium cyanide or K14CN. The radioactive cyanide was used as a marker to easily locate where the cyanide would build up in the fishes' body. Two of the fish were starved for 24 hours prior to exposure; the other one was fed heavily before dosing. They were left in the solution until they were anaesthetized, plus an additional 30 seconds to ensure they were completely knocked out. Immediately afterward, the fishes were euthanized and their brain, gills, stomach, intestine, liver and spleen were removed and weighed. Each organ was then tested for radioactive cyanide.

The results of this small study were interesting. It showed that the single fish with a full stomach concentrated most of the cyanide in its stomach tissue, while the two unfed fishes passed more of the cyanide through their stomach with the majority found in their anterior intestine. Additionally, the stomach contents of the fed fish showed very little cyanide, despite the high cyanide concentrations in its stomach tissue. The author inferred from this finding that cyanide has a specificity for living tissue. From there, the author speculated that a wild fish that is continually grazing would likely have a full stomach. Then, when exposed to cyanide, the poison would be concentrated in its stomach where it would have a greater likelihood of totally destroying the stomach's inner lining. This would destroy its absorptive surfaces and not permit the fish to assimilate food even when feeding heartily.

This experiment also showed another little quirk in the mechanism of cyanide dispersal throughout the fishes' bodies. Of all the organs measured, the brain had the highest mean percentage of recovered cyanide - 33.1%. Whereas the stomach had only 10.4%, the liver had 28.1%, spleen 3.3%, anterior intestine 5.2%, posterior intestine 3.6% and the gills 16.4%. The author then went on to theorize that since the brain has "limited capacity for repair," brain damage from cyanide exposure may account for some of the behavioral abnormalities seen in fish believed to have been exposed to this drug.

In contrast to the previous Bellwood article, this one does mention the number of fish involved in the study - a whopping three! That is not a very large sample size to test. And, there is still no statistical analysis done of the results. Additionally, it would have been interesting to permit more time between the cyanide exposure and the analysis to determine whether the isotopes accumulated. This could have revealed additional clues as to what the long-term effects of cyanide are to fishes that survive their initial exposure.

Hall & Bellwood (1995):

In this paper, the authors seek to further study cyanide exposure in marine ornamental fishes. They state that the previous work done by Bellwood and his results "were equivocal and lacked adequate quantification" and did not rule out other possible causes for the damage found in the intestine and stomach of exposed fishes. They set about studying the effects of cyanide exposure, stress, starvation and various combinations of all these factors on the gastro-intestinal tract.

In this study 154 fish (Pomacentrus coelestis) were collected with barrier and hand nets from the Great Barrier Reef, Australia. Of these, ten fish were immediately killed, and then they performed necropsies taking measurements of various intestinal parameters as a pretreatment control group. The remaining 144 fish were split into nine equal groups of sixteen each for further testing. The first group was a control which was handled as little as possible. The second group was another control group that were handled just like the fish that would be exposed to cyanide, but instead of immersing them in a cyanide water bath, they were simply dunked into a separate container of seawater. The third group was exposed to cyanide at a concentration of 10 ppm for a mean time of 85 seconds plus an additional 5 seconds to ensure a complete effect. The fourth group was a stress group. Whereas all unstressed fishes had a 1,000 cm3 pile of live rock rubble in their tanks, the stressed fish had only one piece of rubble. Additionally, each day the piece was removed for 30 seconds. The fifth group was deprived of any food for the duration of the experiment, 16 days. Then, there were various combination treatments. At the end of the study period, all fish were euthanized, dissected and their intestinal tracts were examined. The results are seen in Table 1 below.

Table 1
Minimal Handling Control
Handled Control
Cyanide & Stress
Cyanide & Starvation
Stress & Starvation
Cyanide, Stress, & Starvation

As can be seen from the table, some of the fishes in the control group perished due to unspecified causes. This severely limits the conclusions which can be drawn from this paper. That said, some interesting conclusions were drawn. First and foremost was that they found no "detectable effect on the intestinal mucosa" of any fish treated with cyanide or stress or a combination of the two. Second, it was found that starvation, alone or in combination with another factor, showed a "statistically significant effect on the fishes' mucosa lining." These starved fishes "displayed a reduction in the mucosal surface area, mucosal thickness and gut length" when compared to all other groups. So, to say the least, this really throws into question Bellwood's earlier contentions. It would seem that if anything harms the gastro-intestinal tract, it is starvation and not cyanide exposure.

There is another important point to be gleaned from this study. The fishes that were exposed to cyanide took 821 ± 86 seconds to recover fully. But, 19% of those fishes failed to recover at all and perished from the cyanide exposure protocol. Additionally, in pilot studies performed prior to this study, fishes were exposed for two minutes. All of these fish failed to recover and perished. So clearly, cyanide can be deadly depending on the concentration and exposure time.

One might be tempted to ignore the mortality figures of the control groups and attempt to decipher a pattern from the treatment numbers alone. I have read other publications that have done as much by selectively excerpting portions of this paper's data. Unfortunately, upon further review, the data only raise additional questions.

If one examines the numbers, starvation has no mortality, stress results in 25% dying, and cyanide killing 37.5%. That seems to coincide with preconceived notions. But, that is where the apparent pattern ends. Cyanide in combination with stress only yields a 25% mortality, which is indistinguishable from stress alone. One would expect that stress killing 25% combined with cyanide killing 37.5% would yield something higher than 37.5% mortality. Additionally, all three treatments (cyanide, stress and starvation) did not result in the highest mortality as one might imagine they would. The highest mortality and the only factor shown to be statistically significant was stress combined with starvation, resulting in 66.7% mortality.

Statistically significant is an important phrase and one that should not be glanced over. Basically, a statistical analysis seeks to determine if the data was the result of simple random chance or the tested hypothesis (Shimek, 2003). Only stress with starvation was shown to be statistically significant. As such, any other pattern one might try to read into the data cannot be ruled out as occurring from random chance or some other unmentioned or unnoticed factor like disease, for instance.

Hanawa et al (1998):

At this point, the literature is unclear about the long-term effects cyanide has on fishes if they survive initial exposure to the drug. The Hanawa et al paper sought to clarify both the acute and long-term effects of cyanide exposure. Additionally, they studied the impact cyanide has in light of research that had been conducted on rainbow trout exposed to sub-chronic levels of a cyanide derivative. These trout "displayed marked anemia." The hypothesis was that fishes exposed to cyanide would have lower hemoglobin concentrations and a lower blood oxygen content. Specifically, they wanted to look at the oxygen consumption rate in the liver as they hypothesized that it would be impaired in fishes exposed to cyanide.

They conducted a series of experiments exposing 60 fishes (Dascyllus aruanus) to cyanide treatments of 25 and 50 ppm for 10, 60 and 120 seconds; there were ten fishes in each group. They found that exposure at 25 ppm for 120 seconds caused 60% mortality and 50 ppm for 120 seconds caused 100% mortality 96 hours after exposure. All other groups (which had shorter exposure times) experienced no mortalities after 96 hours.

Next, they conducted a second series of experiments in which fishes were exposed to 25 or 50 ppm cyanide, but all groups (again, ten fish per group) were treated for only 60 seconds. They added some stressors to some of these groups of fishes to see what results, if any, would occur. There were two groups of fishes; one was exposed to 25 ppm while the other was exposed to 50 ppm, but neither had any additional stress imposed. Another two groups of 25 and 50 ppm exposed fishes were bagged in two liters of seawater for ten minutes before being returned to their aquariums, to simulate transport. The final two groups were intentionally chased with a hand net in their tanks for 10 minutes two and one half weeks after exposure, simulating a retail experience (although, speaking as a former local fish store employee, if you can't catch a damsel from a retail tank in less than one minute, you deserve to be handed your walking papers). None of the groups experienced any mortalities except for the group exposed at 50 ppm for 60 seconds that was bagged. All of those fishes died.

The final criteria they examined were the blood parameters two and a half weeks after exposure. They did not find a statistically different level of blood hemoglobin or blood oxygen levels in exposed fishes compared to the control group. They did, however, find that "liver O2 consumption rates were profoundly affected." They went on to suggest that oxygen consumption rates for the liver or the entire fish could be affected by exposure to cyanide, and that this warranted further study of how that may affect long-term survival after exposure.

Summary of Effects on Fishes:

So, what can we say about cyanide's effects on fish? Well, unfortunately, it is not very clear. We can say that cyanide does kill fish shortly after exposure from acute cyanide poisoning. But, it is unclear what, if any, adverse effects there are on fishes that survive the initial dosage. There are a lot of anecdotal observations of mass mortalities in fishes that were believed to have been exposed to cyanide (Fenner, 2001), but that is not scientific proof.

Studies on Cyanide's Effects on Cnidarians

In contrast to fishes, the effects on corals is much more clear. In every study I have read, corals suffered bleaching or death depending on the dosage used and the duration of the exposure (Jones & Steven, 1997, Jones & Hoegh-Guldberg, 1999, and Cervino et al, 2003). So, regardless of what may or may not occur to fishes exposed to cyanide, it is clearly a destructive practice which should not be encouraged. Be sure to keep that in mind and vote with your dollars for clean and healthy fishes.

Click here for larger image Click here for larger image
Left: Note the apparent cyanide damage to this coral (mid-left), now partially bleached. Right: Apparent cyanide damage to this Acropora colony (upper right). Photos courtesy of Mike Kirda.

Personal Observations on the References:

The one thing that stood out to me in my reading was the inconsistency in the cyanide dosages studied. The dosages varied from a low of 1 ppm all the way up to 5,200 ppm. Similarly, the numerous researchers varied cyanide exposure times from ten seconds all the way up to 30 minutes.

Reference: Concentration: Exposure Time:
Bellwood, 1981a 1 and 5 ppm 120-180 seconds
Hall & Bellwood, 1995 10 ppm 90 seconds
Jones & Steven, 1997 5.2, 52, 520, and 5,200 ppm 60, 300, 600, 1200, or 1800 seconds
Hanawa et al, 1998 25 and 50 ppm 10, 60, and 120 seconds
Cervino et al, 2003 50, 100, 300, and 600 ppm 60-120 seconds

What is even more striking are some of the comments used to describe the dosages employed. Bellwood (1981a) says of his 1 to 5 ppm exposures, "These doses are similar to those believed to be used in commercial fish collecting." In contrast, Cervino et al (2003) states that the much higher exposures of 50-600 ppm "are much lower than those reportedly used by fish collectors." And, Jones & Steven (1997) based their work on an estimate that collectors typically use 10,660 ppm. So, we have one author alleging that 1-5 ppm is the norm for collectors, while another study is saying that collectors usually use more than 50-600 ppm, and a third has an estimate that collectors use 10,660 ppm. Consequently, we are left with the dilemma of which numbers to believe.

For one thing, it's important to note that collectors are typically using rather crude squirt bottles for administering cyanide. As such, they are severely limited in controlling the dosage delivered (Hall & Bellwood, 1995 and Hanawa et al, 1998). Additionally, there is one reference that I found where actual squirt bottles were confiscated and tested (Pet & Djohani, 1998). They showed that the bottles contained dosages of 762.50, 1251.00, 1401.00, and 2017.50 ppm. So, the collectors themselves don't always use a consistent dosage. Moreover, it should be understood that the second this mixture begins to emerge from the squirt bottles, it is instantly diluted with the surrounding ocean water, further changing is concentration. We can still divine a few things, however, by using some common sense. From a collector's standpoint, the goal would be to catch the greatest number of fishes in the shortest amount of time while having the lowest initial mortalities, thereby maximizing profitability. With that frame of mind in place, the early Bellwood article's speculation on dosages seems dubious to me. At 1-5 ppm, it took 2-3 minutes to knock out the fishes. Two to three minutes seems like an awfully long time for a collector to wait to capture a fish. I imagine that a scared and frightened reef fish could travel a great distance from the cyanide fisherman in that amount of time. These fish could easily become quite problematic to locate before the anesthetic effect wore off, not to mention how difficult it would be to maintain that concentration in the open ocean's currents for those periods of time. The same applies to the later Hall & Bellwood paper. On average, it took 85 seconds to anesthetize the fish in that study. Again, that seems too long to me. The Hanawa et al (1998) paper showed that fish could be anesthetized for capture in as little as 10 seconds with 25 or 50 ppm dosages. And it was not until these dosages were prolonged for one to two minutes that the fish suffered 100% initial mortalities. So dosages of 25-50 ppm delivered in short bursts seem the most probable to me. That does not mean, however, that surrounding corals could not be harmed by these dosages. The Cervino et al (2003) paper showed mortalities occurred even at the relatively low 50 ppm concentration studied. Additionally, the initial plume of cyanide might be considerably stronger such that once it is diluted by ocean water that concentration that the target fishes are exposed to is sufficient to anaesthetize them. So clearly, from the research performed to date we can see that fishes and corals can be killed by cyanide exposure depending on the concentration used and the exposure's duration, and that the most likely dosage for effective catch rates would be within this toxic range.

The Scapegoat of Anomalous Losses:

The one thing that frequently bothers me regarding cyanide use is the cavalier way some people throw it around as an excuse for fish losses that they cannot otherwise easily explain. Many times I have read of aquarists suffering mortalities with new acquisitions and blaming the cause on cyanide exposure. "I just lost my so and so. It looked great yesterday, but this morning it was dead. It must have been caught with cyanide." Unfortunately, it takes only a few seconds of further questioning to see that this speculation is false. When a hobbyist makes the accusation that his animal died of cyanide and then happens to mention that the specimen in question was a Hawaiian yellow tang, or an Australian harlequin tuskfish or any other fish that could have come only from a location that is not known for cyanide usage, one can quickly realize that the cyanide assumption was incorrect, although other nefarious or detrimental practices cannot be ruled out.

Screening Suspect Specimens and Selecting Healthy Ones:

Collection Locale:

As I have already alluded to, collection locale plays an extremely important role in avoiding fishes caught using cyanide. As of the time I am writing this piece, I have heard of cyanide usage only in the Philippines, parts of Indonesia, Vietnam, Cambodia, Thailand, the Maldives, Sabah, and possibly the Red Sea (Eritrea) and Tanzania ( Knowing this, and knowing the origin of the fish at the local fish store, goes a long way toward avoiding animals suspected to be captured using cyanide.

Aquarists should realize when looking at the list mentioned above that the International Marinelife Alliance (IMA) compiled of nations that have cyanide usage, does not discriminate between fish caught with cyanide bound for the food fish industry and marine ornamentals caught with cyanide. All locations where cyanide fishing has been reported are listed. That is of particular importance when the Red Sea, particularly Eritrea, makes the list. Eritrea is not an area known for supplying the marine ornamental industry. Fishes hailing from the Red Sea are coming almost exclusively out of Jeddah in Saudi Arabia (Fenner, pers. comm.). So, in general, Red Sea fishes are likely not caught using cyanide because Saudi Arabia is not listed as an offending country for this chemical.

Now, some shops will say they don't know where a particular fish came from. That is only half true. I have seen plenty of availability lists in my decade plus of working in this industry. Every one I have ever seen labels some fish as coming from certain areas. For example, a stock list may have a Hawaiian flame angel. Then, at a slightly cheaper price, a Christmas Island specimen may be listed. And finally, cheapest of all is the generic one with no location noted. It is possible that the wholesaler may not know where that fish came from, but I find that hard to believe. As an importer buying directly from exporters in the country of origin, they must know the flights and from where the boxes of fish are coming from. I find it easier to believe that in those cases they are simply not passing along the information because it is not a positive selling point.

For instance, if someone wants to sell a car, the make and model are pretty standard information proffered. That might be followed by the fact that the car has air conditioning, power windows, power locks, power and heated leather seats, six disk CD player, GPS system, low mileage, etc. But, if the car is old, rusty, has a lot of miles and no air conditioning other than being able to roll down the windows via a hand crank, those things might be left out of the advertisement. The selling point of this vehicle could be its AM-only radio with eight track player and all the Neil Diamond and Barry Manilow tapes the buyer could ever wish for. In one instance, the seller is going to compete on quality, but that quality will come at a price. Conversely, the other seller is going to try to compete via price at a cost in quality.

So it's wise to ask where the fish originated from, but don't stop there. Don't rely on the local fish store as the only source of information. As part of your standard practice of researching potential acquisitions prior to purchase (hint, hint), add to that protocol by finding out the fish's origin. One such reference is It is a free online information site where any inquisitive and responsible person can find a variety of information ranging from a fish's geographic distribution to its full adult size, its gut content analysis and even breeding information in some cases. This way, the purchaser can be armed with the knowledge of where these fish naturally occur so he doesn't get suckered by false information from the local pet store employee. I have been into a lot of pet stores, and there are some notable exceptions, but many of the employees I have met are better qualified to ask if I want fries with that order than to dispense appropriate and correct advice on animal husbandry.

Gross Physical Appearance:
Cyanide caught fishes are thought to have a strange appearance. The easiest way to describe it is that they look too good. Yes, I did state that correctly. "Juiced" fish look really great. They have absolutely fabulous coloration, so much so that they look too good. Have you ever seen a common blue damsel housed in a display utilizing nothing but actinic light? Damsels held in conditions like this almost look like they glow. They have this blue aura surrounding them. In my opinion and experience, as well as that of others (Calfo, pers. comm., Fenner, pers. comm. and Fenner, 2001), "juiced" fish have the same aura-like appearance, even when they are illuminated with standard full-spectrum lighting.

It is also thought that cyanide caught fishes behave strangely as well. A healthy fish should interact with its surroundings. It should react to the approach of potential purchasers or store employees by dashing behind whatever cover has been provided, but at the same time, it should keep an eye on the approaching human. Healthy fish also interact with one another. They typically set up and defend territories while chasing off challengers and intruders. In my experience, fishes that I believe were "juiced" look dazed and confused. They tend to not interact with others in the tank nor do they react much to the presence of people. They sit there mostly motionless, staring off into space.

I have also seen firsthand on numerous instances a store having mislabeled the collection locale of their animals. For example, I recall recently seeing a Hawaiian powder brown tang. The problem was that this specimen was an Acanthurus japonicus, which is not endemic to Hawaii. In fact, the so-called powder brown tang from Hawaii is Acanthurus nigricans. This is a rather innocuous mistake. They probably ordered a Hawaiian powder brown. The wholesaler likely made a substitution to get a good "fill rate" on his order to the store. And, the correct information was never noticed or conveyed to the dealer. But, I have also seen some rather disturbing labeling, such as a tank full of Hawaiian fire shrimp (Lysmata debelius). Worse yet was the Hawaiian Atlantic blue tang my friend Adam Cesnales once saw for sale at a local fish store. That is patently false and, quite frankly, so sad all at the same time. Imagine the poor schooling and general geographical ignorance required to make such a ridiculous assertion.

Species Selection:

It used to be that certain species were notorious for being collected with cyanide. Baby clown triggers are one that comes to mind, for example. They are notorious for being "juiced" as they hide inside corals when frightened, making them difficult to extract. Conversely, other fishes such as clownfish were not reputed to be cyanide exposed because of their intimate relationships with anemones. When frightened, they dive deep into an anemone, but that makes them easy to capture because it is easy to remove a clownfish from a fleshy anemone when compared to removing a Chromis damsel from a branching stony coral head. But I have heard of a disturbing trend of what should be safe fish purchases, such as clownfishes and Banggai cardinalfishes being captured using cyanide (Robinson, pers. comm.). The easiest way to explain this phenomenon is with an old saying, "When all you have is a hammer, everything starts to look like a nail." While a master bass fisherman might be very adept at tempting a largemouth to strike a rubber minnow-shaped, hooked object, he might also be equally ineffective at fly fishing for trout. Cyanide fisherman use cyanide. End of story.

The Other Side

Surprisingly, some authors and editors (Edel, 1982 and Goldstein, 1982 and 1997) don't believe cyanide capture techniques are a problem. They point to the discrepancy in the experimental concentrations delivered as a reason to question cyanide's toxicity. Instead, they insist that poor holding and shipping techniques and related stress, as well as disease, could all be to blame for the greater mortality rates that many in the industry see coming out of areas known for cyanide usage. They point out that the areas most notable for cyanide and high mortality rates are also some of the poorest collection locales. And, they do have a point. Stress was shown to be a significant contributing factor to fish deaths. But, I say, "ak-ro-pore-ah," Eric Borneman says, "a-crop-or-ah." A dead fish is a dead fish is a dead fish. I don't want to waste money on fishes that have a higher likelihood of dying, and I doubt many other aquarists do, either. Whether or not my newly purchased clown trigger dies of cyanide exposure or cyanide and stress or cyanide and starvation or cyanide, stress and starvation or simply starvation and stress is of little consequence to me. They are still dead, and I am out fifty bucks. So, the general principles I outlined in selecting healthy fishes still apply, and I would urge everyone to avoid suspect animals.

Others make the case against cyanide usage from a sportsmanship standpoint (Jonklaas). They argue that somehow it is better to work hard at net catching fish versus using drugs, that there is somehow an unfair advantage to using drugs, and net wielding fishermen are therefore to be applauded and rewarded for their efforts. Again, I couldn't care less. I only want the healthiest livestock, at a reasonable price, caught in a manner which does not damage the reefs. At this time, responsible net collection from areas that subscribe to sustainable collection quotas and "no take" reserve areas fit that bill; indiscriminately squirting cyanide does not. Also, there is the point that regardless of the method used to remove a fish from the wild, it is still removed. To the remaining fish population that removed fish is dead, for lack of a better word (Goldstein, 1982). It will never reproduce and add to the population. It will also not compete for food. And, it will never be returned to the wild.

Last, some question the widespread usage of cyanide from an economic perspective (Edel, 1982). If fish can otherwise be caught without drugs, using drugs that cost extra money does not add up. While that argument may initially seem to make some sense, it is not what actually happens. In many instances, even when net collection training programs are successfully implemented, a significant number of the newly trained collectors have been found to revert to cyanide usage (Rubec et al, 2001). Unfortunately, these fishermen get paid by the fish, regardless of its quality. In effect, it is more profitable to use cyanide to catch a larger number of suspect fish than a smaller number of higher quality ones. And extrapolating that further, catching suspect fish that have a higher likelihood of perishing after purchase also means that more fish will have to be caught to replace those that died. In effect, selling sick fish guarantees job security from the point of view of the cyanide fisherman. But, that assumes that poverty stricken, uneducated fishermen are thinking much beyond the next meal they have to provide for their families. For a more in-depth analysis of the economics of destructive fishing practices see

Ongoing Efforts

A variety of governments, their agencies and non-government organizations are working on this problem. But, I don't really want to talk too much about their work as it is a subject that sparks heated debates and is frankly beyond the realm of what we, as hobbyists, can influence. Instead, I want to focus on what hobbyists can do about this tragedy. First of all, you can educate yourself on the problem. And, if you have read this far, I would say you have made a great first step.

Beyond that, the greatest impact we can provide is to vote with our dollars. Buy captive-bred or tank-raised individuals whenever possible, even when they cost a bit more than their wild-caught counterparts. This segment of the industry is still small and struggling, and is worthy of our financial support.

Also, we must be willing to spend more money on better quality wild-caught fishes. Too many properly trained net fishermen go back to using cyanide because far too many people with fish tanks (note I draw a distinction between someone who owns an aquarium and a true hobbyist/aquarist) are purchasing based on price and not quality. This is an expensive hobby. I know it. I am not well off, so I can sympathize with those who wish to save as much as possible. But those savings should not come at the price of livestock deaths. And in reality, having to buy three or four suspect $30 dollar fish before finding one that actually lives is no savings compared to just buying one healthy $60 specimen.

Second, use the tips and information provided here to avoid supporting the cyanide industry. When you buy wild-caught fish, do everything you can to ensure that they were not captured using this drug. Reward with your purchases the good vendors who sell only healthy, net caught fishes, and punish the bad apples who specialize in cheap, suspect animals by boycotting their stores. I have no sympathy for, and will not be kept up at night over, the thought of unscrupulous or ignorant shop owners going out of business because no one will purchase their suspect animals. It is time to cull the herd and drive these people out of the industry.

Third, do everything in your power to keep the fishes that you buy healthy and long-lived. Every fish that dies in captivity, regardless of the reason, needing replacement puts added pressure on this limited resource.

And finally, attempt to objectively analyze and quantify your successes and failures. Be willing to share that information with others in an effort to contribute to the body of knowledge of aquariology. By educating each other and the general public in the proper husbandry and selection of marine ornamentals, we can make our biggest contribution to saving the reefs that we cherish so much.


I would like to take a moment to sincerely thank Eric Borneman and Dr. Ron Shimek for their assistance with this article. Their editorial reviews are always helpful, but even more so in this case. They both really helped fine tune my voice and clarify the points I wanted to make while using the proper tone. For that, I am genuinely grateful.

If you have any questions about this article, please visit my author forum on Reef Central.


Bellwood, David. 1981a. "Cyanide… An investigation into the long term histological effects of sodium cyanide doses upon the gastro-intestinal tract of Dascyllus trimaculatus, part 1." Freshwater and Marine Aquarium Magazine, November 1981, pages 31-35 and 75-76.

Bellwood, David. 1981b. "Cyanide… An investigation into the long term histological effects of sodium cyanide doses upon the gastro-intestinal tract of Dascyllus trimaculatus, part 2." Freshwater and Marine Aquarium Magazine, December 1981, pages 7-9 and 87-88.

Calfo, Anthony. Pers. comm.

Cervino, J. M., R. L. Hayes, M. Honovich, T. J. Goreau, S. Jones, & P. J. Rubec. 2003. "Changes in zooxanthellae density, morphology, and mitotic index in hermatypic corals and anemones exposed to cyanide." Marine Pollution Bulletin, volume 46, pages 573-586.

Edel, Richard. 1982. "False Alarm on Cyanide?" Pet Age, March 1982, page 4.

Fenner, Robert. 2001. The Conscientious Marine Aquarist. Microcosm/T.F.H. Publications, Neptune City, New Jersey, pages 165-173.

Fenner, Robert. Pers. comm.

Goldstein, Dr. Robert. 1982. "Alternatives to Cyanide: Misdirected Uproar on Drug Use." Pet Age, June 1982, pages 22-25.

Goldstein, Dr. Robert. 1997. "Update on Cyanide." Freshwater and Marine Aquarium Magazine, October 1997, pages 96-102.

Hall, K. C. & Bellwood, D. R. 1995. "Histological effects of cyanide, stress and starvation on the intestinal mucosa of Pomacentrus coelestis, a marine aquarium fish species." Journal of Fish Biology, Volume 47, pages 438-454.

Hanawa, M., L. Harris, M. Graham, A. P. Farrell, & L. I. Bendell-Young. 1998. "Effects of cyanide exposure on Dascyllus aruanus, a tropical marine fish species: lethality, anaesthesia and physiological effects." Aquarium Sciences and Conservation, Volume 2, pages 21-34.

Jones, Ross & Andrew Steven. 1997. "Effects of cyanide on corals in relation to cyanide fishing on reefs." Marine and Freshwater Research, Volume 48, pages 517-522.

Jones, Ross & Ove Hoegh-Guldberg. 1999. "Effects of cyanide on coral photosynthesis: implications for identifying the cause of coral bleaching and for assessing the environmental effects of cyanide fishing." Marine Ecology Progress Series, Volume 177, pages 83-91.

Jonklaas, Rodney. Collecting Marine Tropicals. T.F.H. Publications, Inc. Neptune City, New Jersey.

Pet, Jos & Rili Djohani. 1998. "Combating destructive fishing practices in Komodo National Park: Ban the hookah compressor!" SPC Live Reef Fish Information Bulletin, Number 4, April 1998, pages 17-28.

Rubec, Peter, Ferdinand Cruz, Vaughan Pratt, Richard Oellers, Brian McCullough, & Frank Lallo. 2001. "Cyanide-free net-caught fish for the marine aquarium trade." Aquarium Sciences and Conservation, Volume 3, pages 37-51.

Robinson, Steve. Pers. comm.

Shimek, Dr. Ron. 2003. "A Guide to Building a DIY BS-o-meter." Reefkeeping Online Magazine, June 2003.

Online References:

Analysis of Destructive Reef Fishing Practices in the Indo-Pacific

Anesthesia from Wikipedia

Cleansing Our Seas of a Poison Tide

"Cyanide Fisheries: Where Did They Start?" by Don McAllister, Prof, Ning Labbish Caho and Prof. C.T. Shih.

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Cyanide and Its Unfortunate Use in the Marine Ornamental Industry by Steven Pro -