Pregnancy and Reefkeeping

In honor of Mother’s Day this year in the United States, this post covers the risks of becoming a mother while keeping a reef aquarium.  Last year, I was pregnant with my first child, and I was appalled at the little amount of information available on the topic.  If you’re a male reading this post thinking, “I can’t get pregnant, so I don’t care,” then at least read it for the safety of women and children around you.  Plus, a lot of the medical risks exist regardless of pregnancy.  Hopefully my experience and scientific studies included will help someone!  If you prefer to avoid the scares, you can skip to the bottom for recommendations.

Disclaimer:  I am not a medical-related professional in any capacity.  If you have a medical concern, seek help from a professional.  This article is provided only for basic information and awareness.


An abnormal sense of smell was reported in 76% of pregnant women in a study published by Oxford University Press.[1]  In early pregnancy, I was continuously nauseous.  The smell of “low tide” was practically unbearable and only worsened my nausea.  Water changes were particularly gut-wrenching.  Later in pregnancy, the smell did not bother me as much.


Water weighs approximately eight pounds per gallon (or roughly a kilogram per liter for the rest of the world).  Lifting water for water changes or top-off may be excessive, depending on the health/physical condition of the woman.  I was used to carrying five gallons of water for top-off every couple of days, but later in pregnancy I was unable to safely lift that amount of weight.  Talk to your doctor about how much weight is safe for you to lift.

My tank is a “tall” tank at 31″ high in addition to the 30″ stand.  In order to reach into the tank, I have to use a step-stool.  Medical professionals sometimes frown upon pregnant women elevating themselves due to the risk of falling.  Although a small step-stool may seem like little-to-no risk, I had a non-pregnant friend fall and break her wrist while she cleaned her tank.  Pregnant women may find themselves with less balance than usual due to a change in their center of gravity and loosened ligaments.


Here’s the real problem.  The scientific community knows very little about marine environments, especially how they interact with humans (let alone pregnant humans).  The following information is not meant to scare anyone; it is meant to educate.  As many pregnant women will attest, there is enough scary information out there (eat this, but don’t eat that; work out, but not too much; be calm, but worry about everything!)  There is absolutely no way to avoid all risks.  I educated myself the best I could, and then I made the decision to continue maintaining my aquariums.  My favorite part of reefkeeping is rescuing dying/diseased animals, and due to the risk, I decided to stop rescuing while I was pregnant.  In my opinion, there are too many known pathogens that are transmissible to humans in order to safely treat diseases while pregnant.  Considering how much the scientific/medical community learns every day about pathogens, I did not want to be the first case of some bizarre new disease while pregnant.


For those of you who follow my rescuing endeavors, you probably know how much I hate Vibrio.  It’s a gram-negative bacteria that is incredibly difficult to treat in marine animals.  It often presents itself as sepsis (septicemia), gastrointestinal distress, cholera, and/or open sores.  You can see how destructive this bacteria was to my fish here.  This bacteria is one of the reasons that pregnant women are told to not eat raw seafood.  Some of the antibiotics effective against Vibrio may not be safe for pregnant women, so a less-effective medication may have to be used.  I use Kanamycin on my fish, and this antibiotic is known to cause hearing loss in a developing fetus.  Your doctor will have to weigh the medication benefits/risks against the severity of the infection.[2]


This is another gram-negative bacteria present in marine environments and is usually associated with eating raw seafood.  It can cause granulomas in the brain, and it may present with symptoms similar to meningitis.[3]  Again, the most effective antibiotics may not be safe for pregnant women.[2]


Are you having fun yet?   This bacteria is most commonly associated with Tuberculosis, and it is transmissible from marine animals to humans.  As an example, sea lions at a zoo in the Netherlands were infected with Mycobacterium, and six of their 25 handlers tested positive for the disease.[4]  There have been several documented cases of Mycobacterium marinum infections in reefkeepers (not pregnant), and you can see their disturbing images here.[5]  Additionally, the medications used to treat Tuberculosis cross the placenta to the fetus.[6]


The phrase, “Don’t drink the water when travelling abroad,” is often due to Aeromonas spp. bacteria.  It is usually associated with gastrointestinal distress.[7]  Once again, the drugs required to treat the illness are not entirely safe with pregnancy.


This is a gram-positive bacteria usually associated with animal-occupations (veterinarian, biologist, farmer, etc.)  Usually it presents as a cutaneous lesion, but it can lead to complications.[8]


There are many other bacteria associated with marine environments and animals known to cause disease/illness.  Some of these include Edwardsiella, Salmonella, E.coli, etc.[9]

Bites, Stings, Poison, & Venom:

Unfortunately, this category is too large to discuss in great detail.  Many coral stings may be easily treatable with vinegar followed by hot water, but an eel bite usually requires medical treatment with antibiotics and/or stitches.  Knowing the difference between poison and venom is an important start to the discussion.  Poison is defined as “a substance that through its chemical action usually kills, injures, or impairs an organism,” according to the Merriam-Webster Dictionary.[10]  Similarly, the dictionary defines venom as, “poisonous matter normally secreted by some animals (as snakes, scorpions, or bees) and transmitted to prey or an enemy chiefly by biting or stinging”.[11]  Therefore, venom is essentially poison used intentionally to cause damage.


Palytoxin dangers are highly debated, but regardless of the nuances, it is still one of the most toxic poisons known.  It has a “lethal dose (LD59) in mice of 0.15 microgram per kilogram by intravenous injection”.[12]  It is most commonly associated with palythoas (zoanthids), but it is also associated with dinoflagellates, crabs, fish, etc. (another reason why pregnant women should not eat raw seafood).[13][14][15]  There have been several human fatalities due to palytoxin (usually through ingestion of contaminated seafood).  Further research determined, “its intravenous LD50 in the dog, rabbit, monkey, guinea pig, rat, and mouse range between 0.033 and 0.45 μg/kg.”  This same study determined palytoxin is relatively non-toxic when administered intragastrically.  It is an irritant and can cause tissue damage when applied topically.[16]  While most of us wouldn’t dream of injecting ourselves with palytoxic intentionally, many of us have been poked significantly with vermetid worm tubes or other sharp spines.  Palytoxin is still quite toxic subcutaneously and dermally (so don’t rub a zoanthid on yourself, get tank water in your eyes, or place an open wound into your tank).


Corals contain nematocysts (stinging cells) on their tentacles that inject through human skin like tiny barbs.  The sting from a coral may be painless, feel like an electric shock, itch like poison ivy, or even cause anaphylactic shock.  For instance, fire corals inject a protein venom that causes a burning sensation (hence the name, “fire coral”).[17]

Other animals:

Eels, lionfish, rabbitfish, urchins, and many other animals are known to bite,sting, or otherwise puncture.  Sometimes, even the most innocuous creature will turn for the worst.  I had a bicolor blenny who loved to bite me.  Any open wounds, especially when caused by a marine creature, are subject to infection.  Know what creatures you have in the tank that could create a wound or envenomate.


Many chemical products have a “Material Safety Data Sheet” (MSDS), or as it is now called, a “Safety Data Sheet” (SDS).  These sheets list the ingredients, known hazards, and basic first aid information.  Unfortunately, many of our aquarium products state, “proprietary blend”.  Although unspecified ingredients are still required to have hazard information, there is still some risk due to unknowns (someone might be particularly sensitive to an unspecified ingredient).  Pregnant women should particularly pay attention to the sections on “Teratogenic Effects” and “Developmental Effects”.  These parts states what is known to cause harm to a developing baby.  Since most women are unwilling to have invasive experimentation performed on their babies, there is very little information on the risks of various chemicals.  You can find many of the common MSDS (SDS) through a simple search.  However, I have provided some common ones:

Calcium chloride – anhydrous (used to make calcium supplements):  Teratogenic effects are not available.

Calcium hydroxide (kalkwasser; used to raise calcium and alkalinity):  Teratogenic effects are not available.

Magnesium chloride (used to make magnesium supplements):  Teratogenic effects are not available.

Magnesium sulfate (used to make magnesium supplements):  Teratogenic effects are not available.

Sodium bicarbonate (used to make alkalinity supplements):  Teratogenic effects are not available.

Sodium carbonate (used to make alkalinity supplements):  Teratogenic effects are not available.

CoralRx (coral dip):  Teratogenic effects are not available.

Bayer Advanced Insecticide (used as a coral dip):  “DEVELOPMENTAL TOXICITY: In an oral developmental toxicity study in rats treated with beta-cyfluthrin, decreased fetal body weights and an increased incidence of skeletal findings were observed at the maternally toxic and lethal high dose level (40 mg/kg).”

Levamisole (used as a coral dip):  “DEVELOPMENTAL TOXICITY: Classified Reproductive system/toxin/female [POSSIBLE].”

Lugol’s Iodine (used as a coral dip):  Teratogenic effects are not available.

Red Sea Reef Foundation Test Kit (tests calcium, alkalinity, and magnesium):  “Mg Reagent A contains Sodium tetraborate decahydrate, but at levels below the threshold for classification. This compound has been found to have effects on reproduction and fertility. No compounds present in the reagents have been identified as having carcinogenic, mutagenic properties.”


You can significantly reduce your risks by avoiding aquarium maintenance.  However, if you decide to continue caring for aquariums, then I recommend following the subsequent advice.  Be honest and up-front with your doctor, and take the provided medical advice seriously.  Wear gloves as much as possible.  Less exposed skin is better.  These aquarium gloves are quite popular and are available through Amazon:

If you are fragging, then also wear eye protection (a face mask is advisable as well).  Limit lifting, climbing, or other strenuous activity, especially if your doctor recommends against it.  After aquarium maintenance, wash every exposed body part with hot water (as hot as is safe) and soap.  Scrub thoroughly.  Do not touch your face before you wash.  Also, please do not eat, drink, or smoke while performing aquarium maintenance (or smoke at all while pregnant).  This will help limit ingestion of poisons/bacteria.

Be familiar in first aid, and have those in your household also become familiar in first aid.  For any injuries, contact medical personnel.  Typical treatment for most aquarium stings/bites/etc. is to soak the area in vinegar for about 15 minutes, followed by a soak in hot water (as hot as you can safely withstand without burns) for about 30-90 minutes.  The vinegar will help dissolve the nematocysts and prevent them from further discharging.  Many poisons/venoms are broken down by heat (although some are intensified with heat, so contact medical personnel!)[18]  If you develop any rashes, lesions, or develop odd symptoms (loss of vision, heart palpitations, wheezing, numbness, etc.), then also contact medical personnel immediately!

Stay up to date on your immunizations (particularly tetanus if you plan to continue reefkeeping).  Make a list of your aquarium inhabitants and potential exposures, and provide this to your doctor.  I also kept a list of these things along with other relevant medical information in my purse.  Sometimes medical issues will surface long after the initial exposure, so it’s important to have the information written in case you are unable to relay potential exposure information.

After the baby is born, make sure the aquarium area is baby-proofed.  Curious little hands will find every hazard!


Although I continued to perform aquarium maintenance, I stopped rescuing coral/fish due to the increased risks.  I experienced no aquarium-related injuries and had a healthy baby.  Although this is not a comprehensive list of marine hazards to a developing baby and its mother, hopefully it is an educational start.  Reduce the risks where possible, and if you must accept some risk, be prepared on how to handle it.  Good luck!

If you can think of other hazards, let me know in the comments!

Image courtesy of WWW.ALANLOUIE.COM & www.a2creativestudio.com.


  1. Nordin, Steven, et al.  “A Longitudinal Descriptive Study of Self-reported Abnormal Smell and Taste Perception in Pregnant Women.” Chemical Senses (2004) 29 (5): 391402.
  2. Norwitz ER, Greenberg JA. “Antibiotics in Pregnancy: Are They Safe?”  Reviews in Obstetrics and Gynecology. 2009;2(3):135-136.
  3. Sohn AH, Probert WS, Glaser CA, et al. “Human Neurobrucellosis with Intracerebral Granuloma Caused by a Marine Mammal Brucella spp.”  Emerging Infectious Diseases. 2003;9(4):485-488.
  4. Hu, G, et al.  “Meta- and Pooled Analyses of the Effect of Glutathione S-transferase M1 and T1 Deficiency on Chronic Obstructive Pulmonary Disease.”  The International Journal of Tuberculosis and Lung Disease 12, no 12, December 2008, 1474-1481.
  5. Pro, Steven.  “Mycobacterium marinum:  The Fish Disease You Could Catch”, Reefkeeping, 2003, http://www.reefkeeping.com/issues/2003-07/sp/feature/.
  6. Centers for Disease Control and Prevention, http://www.cdc.gov/tb/publications/factsheets/specpop/pregnancy.htm, accessed 2 May 2015.
  7. Vila J, Ruiz J, Gallardo F, Vargas M, Soler L, Figueras MJ, et al. “Aeromonas spp. and traveler’s diarrhea: clinical features and antimicrobial resistance.” Emerg Infect Dis [serial online] 2003 May.
  8. Reboli, A C, and W E Farrar. “Erysipelothrix Rhusiopathiae: An Occupational Pathogen.” Clinical Microbiology Reviews 2.4 (1989): 354–359. Print.
  9. Clarridge, J E et al. “Extraintestinal Human Infection Caused by Edwardsiella Tarda.” Journal of Clinical Microbiology 11.5 (1980): 511–514. Print.
  10. “Poison,” http://www.merriam-webster.com/dictionary/poison, accessed 10 May 2015.
  11. “Venom,” http://www.merriam-webster.com/dictionary/venom, accessed 10 May 2015.
  12. Richard E. Moore and Paul J. Scheuer, “Palytoxin: A New Marine Toxin from a Coelenterate,” Science, 30 April 1971: 172 (3982), 495498.
  13. Arthur M. Kodama, Yoshitsugi Hokama, Takeshi Yasumoto, Masakazu Fukui, Sally Jo Manea, Neal Sutherland, “Clinical and laboratory findings implicating palytoxin as cause of ciguatera poisoning due to Decapterus macrosoma (mackerel),” Toxicon, Volume 27, Issue 9, 1989, Pages 1051-1053.
  14. Angel C. Alcala, Lawton C. Alcala, John S. Garth, Daisuke Yasumura, Takeshi Yasumoto, “Human fatality due to ingestion of the crab Demania reynaudii that contained a palytoxin-like toxin,” Toxicon, Volume 26, Issue 1, 1988, Pages 105-107.
  15. Yutaka Onuma, Masayuki Satake, Takanori Ukena, Jean Roux, Suzanne Chanteau, Noelson Rasolofonirina, Mamy Ratsimaloto, Hideo Naoki, Takeshi Yasumoto, “Identification of putative palytoxin as the cause of clupeotoxism,” Toxicon, Volume 37, Issue 1, January 1999, Pages 55-65.
  16. J.S. Wiles, J.A. Vick, M.K. Christensen, “Toxicological evaluation of palytoxin in several animal species,” Toxicon, Volume 12, Issue 4, August 1974, Pages 427-433.
  17. Eric Borneman, “Venomous Corals:  The Fire Corals,” Reefkeeping, November 2002.  http://reefkeeping.com/issues/2002-11/eb/
  18. “Marine Animal Bites or Stings,” http://www.nlm.nih.gov/medlineplus/ency/article/000032.htm, accessed 10 May 2015.


  1. Thomas

    Wow, excellent information! My wife is 8 weeks along with our second child. Your article is the first I’ve heard of these precautions. Thank You!

    1. admin

      I’m so glad it helped! I was in the same boat with no information, and I didn’t want others to be without it too. Congrats on your growing family, and good luck!

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