by Pete Giwojna and Carol Cozzi-Schmarr
from the September 2003 issue of FAMA
I heard that Hippocampus capensis seahorses are carriers of fish tuberculosis and should never be kept with other seahorses. Is that true? I’m a little worried about this because I know fish TB is a disease you can pick up from your aquarium, and I own 2 pairs of Zulu-lulus. Do captive-bred Zulus carry fish TB, too, like wild capensis? What sort of precautions should I take with my Zulus?
Thank you for bringing your worries regarding fish tuberculosis to my attention. In the last few weeks I’ve had quite a flurry of questions about fish tuberculosis from concerned Zulu keepers, and I would like to put everyone’s minds at ease.
The short answers to your questions are as follows:
Yes, Hippocampus capensis is indeed susceptible to fish TB (Mycobacteriosis).
No, captive-bred Zulu-lulus absolutely do not carry it!
Let me emphasize that once more for good measure before I go on, Kerry: Zulus do NOT carry fish tuberculosis and there is no risk that Zulu owners might acquire this disease from their seahorses!
Although Zulu keepers have nothing to fear in that regard, you are right to be concerned about Mycobacteriosis, Kerry, since piscine tuberculosis is one of the few forms of fish disease that is communicable to humans. This transmission usually manifests itself as an unsightly skin rash involving one or more granulomas on the arms of the fish-keeper. In severe cases, these nodules of inflamed tissue can become large and disfiguring. They can spread, and are very difficult to eradicate, leaving some victims disfigured for life. The granulomas often take some 2-4 weeks after exposure before manifesting themselves, so the individual is frequently unaware of how he or she contracted them and the condition very often goes undiagnosed. The Mycobacteria that cause the disease typically gain entry through a break in the skin such as a cut, scrape, or abrasion on the hand or arm of the aquarist. Although unsightly, the granulomas themselves are not serious problem and are almost always localized in healthy individuals. But for those of us whose immune systems are compromised by AIDS, kidney disease, diabetes, liver dysfunction, chemotherapy or the like, the infections can sometimes become systemic or, on rare occasions, even life threatening.
Awareness is the appropriate response to the risk posed by fish tuberculosis. The seahorse keeper should be aware of the remote possibility of being exposed to Mycobacteria via his aquarium, and take appropriate precautions, but there is certainly no cause for alarm, as explained below. Here are the facts about Mycobacteriosis, Kerry:
Mycobacteriosis is also known by the following synonyms: fish tuberculosis, piscine tuberculosis, granuloma disease, swimming pool granuloma, fish tank granuloma, and acid-fast disease.
Fish tuberculosis is caused by pathogenic Mycobacteria, of which two different types are the primary culprits: Mycobacterium marinum and Mycobacterium fortuitum. Unlike most bacteria the plague fish, these Mycobacteria are gram-positive, and take the form of pleomorphic rods that are acid-fast and nonmotile.
Mycobacteriosis is worldwide in distribution. All fish species are considered susceptible to it. Although this disease can in fact infect almost all fish, certain species are more vulnerable than others. The most susceptible species are freshwater tropicals such as black mollies, all gouramis, neons and other tetras, all labyrinth air breathers, and most species of the Carp family (goldfish and koi, for example).
Mycobacteria are ubiquitous and waterborne, and the aquatic environment is considered the disease reservoir for fish tuberculosis. Mycobacterium marinum has been cultured throughout the world from swimming pools, beaches, natural streams, estuaries, lakes, tropical fish tanks, city tap water and well water. Human epidemics of granulomatous skin disease have occurred from swimming in infected water, and in fact, this mode of human infection is far more common than infection from exposure to infected fish tanks.
Mycobacteriosis is a chronic fish disease that progresses quite slowly. It may take years for an infected fish to develop any symptoms of apparent illness and much longer before it becomes fatal. The glacial progression of the disease makes it difficult to diagnose. Some early signs to look out for include lethargy, fin loss, emaciation, skin inflammation and ulceration, edema, popeye, and peritonitis. In later stages, nodules may develop in muscles and deform the fish.
As difficult as slow-moving TB may be to diagnose while the infected fish is alive, once the victim expires, postmortem examination will reveal clear, unmistakable signs of Mycobacteriosis. The telltale granulomas will appear as gray or white nodules in the liver, kidney, heart or spleen. There is often black, necrotic tissue eating away at the internal organs, and there may also be skeletal deformities. Diagnosis is then confirmed by the presence of acid fast bacteria in tissue sections.
Treatment and Control:
The pros treat Mycobacteriosis using a combination of doxycycline and rifampin, but those are prescription drugs that most likely will be unavailable to home hobbyists.
The average aquarist will have better luck treating tuberculosis with a combination of Isoniazid, Kanamycin, and Vitamin B-6 for at least 30 days. Liquid baby vitamins are a good source of vitamin B-6, and can be added to the hospital tank at the rate of one drop per every 5 gallons of water. Be sure to replace the vitamins after each water change in the treatment tank.
Transmission: the bacteria can be transmitted through the water from open ulcers, through contaminated food (including live foods such as shrimp or molly fry), via feces of infected fish, or through the consumption of infected, dead or dying fish in the tank (although this does not apply to seahorses).
Contributing factors: this disease is not highly contagious and does not seem to spread from fish to fish. However, fish TB it is often associated with poorly kept or dirty tanks with poor water quality. Chronic stress from factors such as overcrowding, malnutrition, or aggressive tankmates often plays a role as well.
Mycobacterium, the causative organism, is believed to be ubiquitously present, making it very difficult to eliminate it entirely. However, if good aquarium maintenance and management is followed, including vacuuming of the gravel along with good filtration and regular water changes, combined with a nutritious diet and the addition of an enrichment product rich in vitamins, the problem can be minimized and eliminated as a cause of mortality. Any dead fish should quickly be removed and disposed of properly. Diseased live fish should be isolated and treated in a hospital tank.
Those are the basic facts about fish TB, Kerry. I know it can be disconcerting to think that your fish tank could make you sick, but the risk is vanishingly small and the rewards of fish keeping are very great. How small is the risk of contracting Mycobacteriosis from your seahorses? To put things in the proper perspective, it may help to remember the following:
You are far more likely to be exposed to Mycobacteria when you go swimming at the beach or your neighbor’s pool than from your fish tank.
Statistically, your drinking water or bath water is more likely to be a source of Mycobacteriosis than your aquarium.
Your kid’s goldfish bowl, the tank of neon tetras with the pair of kissing gouramis at the doctor’s office, and the koi pond at the mall are all bigger threats of fish TB than your seahorse setup.
So should we be worried about contracting fish TB from our seahorses, Kerry? Do we worry about it when we’re cleaning the betta’s bowl? Do we worry about it when we go swimming? Or when our kids are admiring the freshwater tropicals at the LFS? Of course we don’t. Then we certainly need not be overly concerned about it when it comes to our seahorse tanks.
The aquarist should merely remain aware of Mycobacteria and follow the usual sensible precautions. Nets, aquarium accessories and equipment, and any other items that may come in contact with the fish should be sterilized between uses to prevent cross-contamination. Make full use of aquarium gloves and don’t place your hands or arms in the aquarium if you have any cuts or scrapes. Handle sick fish carefully, dispose of deceased specimens properly, and scrub up afterwards. Do NOT dispose of dead fish by flushing them down the toilet, as this is a prime way to spread disease. Place the fish carcass in a plastic bag or wrap it in some foil and dispose of it with the solid waste of the household. And don’t feed dying fish to larger carnivorous fish, since this an excellent way to spread infection.
One thing hobbyists who are worried about fish TB can do to allay their concerns is to get their seahorses and live foods (crustaceans such as shrimp are known vectors for Mycobacteriosis) from a High Health facility such as Ocean Rider rather than from their LFS. I can say with absolute certainty that Zulu-lulus do not carry tuberculosis because all Ocean Riders are routinely screened for pathogens and parasites by independent examiners from an outside agency (DVMs with the Department of Agriculture). The latest screening was recently completed and included a representative sample of 20 Zulu-lulus, which were sacrificed specifically for this comprehensive testing.
As usual, the lab results were completely negative. With regard to Mycobacteriosis (fish TB), the multi-organ histopathology showed no granulomas and the tissue sections revealed no acid-fast bacteria. That is conclusive evidence that tuberculosis is not present. The captive-bred Zulus are now in their eight generation, and if they have not shown any clinical signs of fish TB in all that while, as confirmed by tissue sections and histopathology, we know they do not carry the disease.
In fact, from now on, Kerry, the Department of Agriculture is going to certify that Zulus are SPF for fish tuberculosis (Mycobacteriosis), and Ocean Rider is going to start sending out certificates to that effect with every Zulu order as soon as possible. Knowing that Zulu-lulus are officially Specific Pathogen Free with regard to Mycobacteria should erase any worries hobbyists may have had in that regard.
In other words, Kerry, you don’t need to take any special precautions with your Zulus. They cannot give you granuloma disease. By all means, feel free to mix them with compatible seahorses, feed them by hand, and work in their aquarium as needed without any qualms. Just follow the same common-sense precautions all diligent aquarists observe and you’ll be fine.
Best of luck with your Zulus, Kerry!
I’m very interested in ordering some seahorses, but I have reservations about one thing in particular. My job keeps me very busy at the moment, and I have no time to spare for raising the babies. Will the seahorses be happy if I keep only females (or all males)? I know they form strong attachments to their partners, and I don’t want to do anything that will cause them stress.
Let me reassure you that you are not alone in your dilemma. Many seahorse keepers are unable to provide the time and effort rearing requires, particularly since a breeding pair can produce a new brood of babies (hundreds of fry) every month.
In that case, some hobbyists do indeed prevent their seahorses from breeding by segregating the sexes and keeping males and females in separate tanks, or by ordering seahorses that are all the same gender. Others allow their seahorses to breed, which gives the aquarist a chance to observe their amazing courtship displays and mating rituals, as well the miraculous spectacle of the male seahorse giving birth, but sacrifice the newborn fry by allowing hungry tankmates (compatible fishes and inverts, not the other seahorses) to make a meal of them. It sounds heartless and cruel, I know, but that’s precisely the fate most seahorse fry suffer in the ocean. At very best, only one or two seahorses from each brood survive to maturity in the wild; the rest are lost to predators. Most people feel the parents are much happier in the aquarium if allowed to pair off and mate, so when aquarists are too busy for rearing fry, most hobbyists simply let nature take its course and eliminate the newborns as forage for bigger fish.
I think that’s the best solution, both for the seahorses and their keepers. The seahorses enjoy a richer, more natural life when they have the opportunity to interact, court one another, pair up and reproduce. And the hobbyist has a chance to observe social interactions and behaviors he would otherwise never see, such as competition for mates and daily greetings and birthing, including one of the grandest spectacles in all of nature — the colorful courtship and mating ritual of the seahorse!
Over a period of three days, the partners perform a series of ritualized maneuvers and distinct displays — brightening, reciprocal quivering, pumping, pointing, and several delightful dancelike displays (the carousel dance, Maypole dance, and the parallel promenade) — all culminating in the copulatory rise and exchange of eggs. Once a pair has bonded, these maneuvers are repeated regularly in a daily greeting ritual that strengthens and reinforces the pair bond. In my opinion, Paula, the seahorses have a better quality of life when they are allowed to engage in these activities in the aquarium, even if it means sacrificing their young.
Some hobbyists have a friend or neighbor or know a fish guy from the local pet shop who is interested in rearing, and allow them to take home their seahorse fry and raise them. Some hobbyists even ship the fry to breeders elsewhere who are set up for rearing. That may be another possibility you can explore down the road, Paula.
Allowing the seahorses to breed freely also leaves the door open for you to try your hand at rearing someday, Paula. Once you gain a little more experience and confidence keeping seahorses, there will likely come a time when you feel you’re ready for the challenge of rearing. Sooner or later, most seahorse keepers decide to try their hand at raising them. When that day arrives, you will already have breeding pairs ready to give you plenty of fry to rear.
Best wishes with all your fishes, Paula!
Pete Giwojna, Ocean Rider Tech Support
I have purchased a mated pair of Zulus with a pregnant male. Can you tell me something about the breeding habits of Hippocampus capensis? I am also wondering what to feed the babies when they are born? If I give them live food, will they learn to eat frozen mysis later on? Any rearing tips, if you don’t mind me asking?
Thanks for your help.
Congratulations on your pair of Zulu-lulus (Hippocampus capensis), sir! You have now joined a very select group of hobbyists who are entrusted with the stewardship of the most endangered seahorse in the world. You will find that these remarkable rarities court constantly and breed like bunnies, Pete.
They seem to be strictly nonmonogamous, at least in captivity, although they will form short-term pair bonds. From talking with breeders, I understand that when you keep them in mixed groups, one male tends to do all or most of the breeding. But that’s part of what makes keeping them so much fun — they court nonstop, each trying to outdo the others for that honor. So the Zulu keeper gets to see a lot of fascinating social interactions and interesting behaviors most seahorse keepers never observe.
The gestation period for H. capensis is about 21 days, perhaps a bit shorter if you’re keeping them at temps in the mid-70’s. Brood size is about 150 to 200 with the exceptional large brood of around 300. The fry are quite large, usually 8-10 mm in total length. They grow very fast and reach sexual maturity as early as 10 to 12 weeks.
Compared to most other seahorses, rearing these chubby little chowhounds is a breeze. Little ‘lulus are the most benthic of babies and thrive on newly hatched brine shrimp from Day One. Just feed them plenty of baby brine shrimp as soon as possible after the Artemia hatches and they will grow like weeds. They will be ready to be weaned onto frozen mysis by the age of six weeks. They make the transition from live food to frozen fodder remarkably easily, without missing a beat!
I would recommend keeping the babies in a bare-bottomed nursery tank with an air-operated sponge filter or foam filter until they are six week old and weaned onto frozen mysis shrimp just like their parents. The baby brine shrimp the little ‘lulus require is simply too insignificant to interest the adults. Keep the temp at about 75-degrees F — no warmer than 77 F.
The nursery tanks can be small — 2-gallon aquaria or 2-1/2 gallon drum fishbowls will do nicely. They should be filled with water taken from the ”paternity ward” — the same tank the fry will be born in — so the delicate newborns can be transferred directly to the nursery without adjusting to any stressful changes in pH or salinity.
Cured ”seahorse trees” make good hitching posts for a nursery, as do artificial aquarium decorations such as small seafans and soft plastic plants with fine, branching leaves. If necessary, the holdfasts can be secured to the bare glass with silicone aquarium cement or suction cups designed for use in marine aquaria.
If you can obtain it, live Caulerpa will help maintain good water quality by removing excess nitrates, as well as providing natural hitching posts that help seahorses feel right at home. These marine plants grow from woody holdfasts and don’t need to be anchored in a sand or gravel substrate.
Good lighting is also essential for the nursery tanks. The fry must be able to see the tiny organisms they live on clearly in order to feed efficiently. Use ”Daylight” fluorescents and leave them on for a minimum of 14-17 hours a day, since the fry need to eat for at least 14 hours everyday. Some breeders provide the young with 24 hours of light a day so they can feed continuously around the clock during the crucial first 6 weeks of their lives. As soon as they are eating frozen mysis, the little ‘lulus can go back in the main tank with their parents.
One other thing Zulus keepers should be aware of is the fact that these galloping gourmets are real bottom huggers. Not only do they stick to the lower levels of the tank and orient to the substrate, they will often slink along the bottom on their bellies and curl their tails behind them. They usually won’t eat from the water column, much preferring to allow their food to settle on the substrate where it can be examined closely and eaten at their leisure.
Here’s how Neil Garrick-Maidment, an extremely successful breeder with the Seahorse Trust in the UK, describes the benthic behavior of Cape seahorses (Hippocampus capensis):
They’re an amazing Seahorse. I kept them for some time and bred thousands of them; in fact the ones you have are probably descendants of them.
Like you say they are intriguing as they tend to live on the bottom most of the time and the young in particular drop like stones when they are born and hold on from day one. If there is a Seahorse that is suitable as a first time one then it has to be the Knysna Seahorse (Hippocampus capensis). The brilliant thing about them, in the wild they naturally feed on nonmotile food so it makes them a god send for training onto dead food and the young do really well on newly hatched Artemia, without enrichment.
They come from the Knysna and Kuerbon lagoons in South Africa and due to the seasonal flooding in that region it means that they can cope with a wide range of salinities including I am told freshwater for a very short length of time (personally I wouldn’t try this).
They were the first Seahorse to be listed on the South African red data list as ironically for an animal that breeds so well they are down to just a few hundred in the wild.
The ground dwelling behaviour is perfectly normal for them, in fact many people are disappointed when they spend all their time on the bottom, having said this, a tank of a minimum of 15 to 18 inches is better for egg swapping. apart from the two British species, Knysna seahorses have got to be my favourite.
At any rate, Peter, because of their bottom-hugging behavior, it’s very important to keep the substrate scrupulously clean for these bottom feeders. Use a feeding station and clean up leftovers promptly. Avoid crushed shell or crushed coral and the like, and select a fine-grained, nonabrasive substrate for Zulus instead. Fine sugar sand works well for these little tail draggers. Don’t allow detritus to build up and vacuum the sand bed often.
Best of luck with your Zulus, Peter!
How can I get a Health Certificate with my Zulu-lulus?? I want to make sure my seahorses are certified.
All Zulu-lulus will come with a health certificate that is updated periodically by the State of Hawaii Aquaculture Disease Program after examining the Ocean Rider Farm and Livestock to ensure they are compliant with current health standards. The Health Certificate will state that the seahorses are free of mycrobacteria, internal bacterial infections and parasites.
My male Zulu-lulu has gone from the grey, black color and has now turned to more of a dark mustard yellow. Is this something I should be concerned about. It is the color he turned when he was courting the female. I thank you in advance for any help and info you may be able to give me.
That is fantastic! The color change you are seeing is not only completely normal and a sign of excellent health but the envy of all seahorse hobbyists!! He may even turn to a bright yellow like in the photo by Leslie Leddos yellow male Zulu-lulu in last month’s Horse Forum column. Most seahorses have the ability to change color with the proper tank environment. Typically they will turn brighter colors during mating like you are seeing and darker colors when stressed or under non-spectacular tank conditions. What is amazing to me is how fast they can and do change color, so enjoy the courting colors!!