This FAQ is mostly concerned with the care and upkeep of the Potbelly or Southern Knight seahorse (Hippocampus abdominalis). This is the most common and widely accessible species of captive-bred seahorse. Much of the information, however, is still applicable to other species, and some information on other species is included for comparison. As more captive-bred species become more widely accessible, this FAQ will be extended to include more particular information on their care.
Southern Australia boasts a greater diversity of marine life than the Great Barrier Reef, yet our wonderful locals are seldom housed in aquaria. Many temperate marine animals are difficult to keep and must frequently be collected; nevertheless, if you want a bit of South Australian marine life in your house, pot-bellied seahorses are the way to go! These endearing critters are simple to care for, and since they are now captive-bred, they are widely accessible, well-adapted to captivity, can survive a broad variety of temperatures, and may be maintained without permission.
About the Potbelly Seahorse
Potbelly seahorses (Hippocampus abdominalis), commonly known as bigbelly or Southern Knight seahorses, are the biggest and longest-living seahorse species.
They have a broad range in the wild, including the seas near New Zealand, Tasmania, Victoria, South Australia, and New South Wales. However, specimens for the hobby are currently being captive-bred in a variety of locations around Australia.
In locations with colder water, their maximum size is bigger, and they may reach up to 35cm in the seas near Tasmania and New Zealand. Other locations’ specimens seldom surpass 25cm, and their greatest size in aquaria is usually a little more than 20cm.
They can withstand a broad variety of circumstances, including varied temperatures and salinities ranging from 1.015 to 1.027 (measured as specific gravity), and captive-bred animals may endure relatively high temperatures following acclimatization. They do, however, need clean water and enough oxygenation.
Potbelly seahorses get their name from their large bellies, which are shared by both males and females. They are distinguishable from other seahorses by their size, belly, low crown, and long tail. Their skin tone ranges from tan to yellow, with darker spots. White and brown specimens are sometimes observed, as are red animals, although these are quite unusual. They often feature head spikes, which are formally termed cirrii and are more abundant and numerous in males.
Potbellies, unlike many other seahorses, do not create strong pair ties and are not monogamous. They are also much more sociable with other members of their species (both same and opposite sex) than most seahorse species. They are often encountered in huge groups in nature, and they will interact rather sociably in the aquarium. They may be maintained alone, but it is more fascinating to study their interactions and social behaviors when they are kept in couples or groups.
How long do they live?
Potbelly seahorses are one of the seahorse species with the longest lifespan. Individuals in the wild may survive for up to 9 years on average. Because they have only been captive-bred for a few years, their potential longevity in captivity is unknown, although it might be substantially longer. Other species have lifespans ranging from one to four years, with medium and bigger species (e.g., Hippocampus kuda) often outliving smaller ones.
Can you tell male from female and do they breed in the aquarium?
In adult seahorses, there are clear sexual distinctions, although they are not always visible in juveniles. The entrance to the brood pouch on the male seahorse gives the belly a characteristic form with a prominent “lump” at the top (see left), while the female has a smooth profile to her belly (right).
Both sexes may have head spikes (cirii), although males have more of them and they are frequently more numerous. Males have significantly darker and more pronounced markings, although since coloration varies so much, this is not necessarily a distinguishing trait.
Although seahorses are now captivity-bred, breeding in the home aquarium is very unusual. They may, however, be seen doing courting rituals, with the male inflating his belly and displaying it to females.
Water quality requirements
Potbelly seahorses, as previously stated, can endure a wide variety of temperatures and salinities. The temperature should be between 18 and 24°C, pH 8.2, and specific gravity (a measure of salinity) should be between 1.020 and 1.024. Captive-bred individuals, on the other hand, can endure temperatures as low as 12°C and as high as 32°C following acclimatization, as long as the water is sufficiently oxygenated at higher temperatures. Seahorses are more susceptible to temperature stress during and soon after travel, thus it is best not to relocate or introduce them on very hot days, and to carry them in an insulated container (e.g., an esky or a polystyrene box). For additional information on temperature and how to regulate it).
Although they can tolerate a broad variety of salinities, proper filtration and water quality are essential. To remove ammonia and nitrite, biological filtration (see next section) should be utilized, and frequent water changes are required to remove nitrate and maintain pH steady. The water should be adequately oxygenated as well. While most decent filters will do this, it is a good idea to run an airpump, in addition, to providing enough aeration, especially in hot weather. Furthermore, they are sensitive to rapid changes in salinity, so be careful to acclimate them after transit and do water changes using a salt water mix of the same salinity as in the tank.
Filtration for seahorses
Seahorses, like any saltwater fish, need adequate filtration, although they are not great swimmers and do not enjoy too strong a current in the aquarium. Overflow filtration is often the best option for tanks of up to 100 liters. These filters offer excellent water turnover and oxygenation while using less current. It is recommended to choose a model that either employs a specialized biological filter medium or allows for partial media replacement at a time to sustain biological filtration. Canister filtration is suggested in bigger tanks owing to its ability to offer additional biological filtering. Most types may be equipped with a spray bar to ensure that the water flow is distributed and not excessively powerful.
All-in-one aquaria with over-tank trickle filtration are typically fine for seahorses. These filters provide excellent biological filtration and, once again, a moderate current. Whatever technique is selected, a sponge filter should be installed at the intake so that food particles are not sucked into the filter before the seahorses have had a chance to feed.
Because seahorses do not create as much waste as certain fish, a three to five-hour rotation is generally sufficient. If you want to maintain invertebrates with your seahorses, you may need to enhance filtration or add protein skimming.
The aquarium & other required equipment
The tank for seahorses does not need to be too huge; in fact, they are simpler to care for in a small tank. The lowest size suggested is around 25 liters. A tank with a capacity of 50 to 150 liters is excellent. Bigger tanks may make it difficult for the seahorses to reach the food, but these sizes are appropriate for maintaining larger numbers, such as more than six seahorses.
Seahorses prefer deeper aquariums than longer ones. The depth should be at least 12″ (30cm), preferably 18″ (46cm). (A depth of around 24″/60 cm is normally needed for breeding, although it is not required for day-to-day seahorse care.)
The tank should be completely glass or acrylic; older steel frame tanks (which are no longer available new) are not suited for saltwater. Choose a location for your aquarium that is not in direct sunlight. Excessive light not only increases algae development, but it may also cause overheating. It is also advisable to keep your seahorses in an airconditioned environment to make temperature regulation simpler (for more tips on temperature control, see here).
Because potbelly seahorses can survive a broad variety of temperatures, heating is seldom required. However, since seahorses dislike temperature swings, you may wish to add a low-temperature heater to offer a more steady temperature. If you want to keep invertebrates with your seahorses, you may need to install a heater (more info).
In addition to the aquarium and filtration, you will need synthetic sea salt, a hydrometer, and other testing equipment, substrate, and decorations. You might also add an air pump or lights.
Synthetic sea salt: Synthetic sea salt is necessary to generate salt water. For the reasons stated above, collecting your own saltwater is typically not suggested. Synthetic sea salt is simply added with known weight per liter of tap water (usually 33 grams of salt per liter). A high-quality water conditioner should be utilized as well.
The hydrometer determines specific gravity, which is determined by salt concentration. This is required to confirm that the salinity is right before adding seahorses, as well as to check for evaporation. Salinity rises due to evaporation, and freshwater should be provided to compensate (more info).
Additional testing equipment: Seahorses, like other fish, create ammonia, which is broken down by filtration into nitrite and subsequently nitrate. Both ammonia and nirtite are harmful to seahorses and should be tested on a regular basis to verify filtration is sufficient and operating correctly. Because the bacteria that break down ammonia and nitrite are present in limited quantities when the tank is first set up, more attention is required. Although adding a bacterial supplement is highly suggested to seed the filter with healthy bacteria, you should still keep a watch on water quality and execute a water change if ammonia concentration surpasses 0.05ppm hazardous ammonia or 0.3ppm nitrite. More information about water testing may be found here.
Substrate and decorations: One of the characteristics of seahorses is their prehensile tails, which they employ to anchor themselves. Seahorses like to have something to cling to and will not be content in a naked tank. They aren’t picky about what they utilize; plastic plants, silk plants, and most aquarium decorations are OK but avoid anything with sharp or rough edges. Marble, shellgrit, or coral sand are the ideal substrates to utilize. Because they are made of limestone, they assist to keep the pH stable. Other aquarium gravels are okay to use, but they lack essential pH buffering. Rocks such as limestone, slate, and sandstone may also be utilized as décor.
Air pump: Because seahorses need highly oxygenated water, having an air pump in addition to filtration is advised. If the bubbles created are too fine, the seahorses may mistake them for food particles and consume them, causing flotation issues. Diffusers with bubble walls work nicely, or you may bury an airstone in the gravel or behind a rock to produce bigger bubbles.
Lighting is not required for seahorses, however, it is usually preferable to light the aquarium and make the seahorses more apparent. Fluorescent lighting is ideal since it is energy efficient and has a pleasing spectrum. A single high-intensity aquarium tube produces the greatest results.
Transport and acclimatisation
When shipping seahorses, greater care must be used than when transporting other fish. They can tolerate lengthy voyages if properly packed, although they are more susceptible to high temperatures and temperature variations during and after shipment. As a result, it is advisable to transport seahorses in an insulated container, such as a polystyrene box or esky, particularly on hot days, such as when the temperature exceeds 30°C (or 25°C if an insulated container is not used).
When brought to a new aquarium, seahorses may get stressed if the water is warmer than the water from which they came. Check the tank temperature before floating the bag. If it is more than two or three degrees warmer than the water from which the seahorses came, or if it is over 25°C, do a water change or float some ice cubes in a bag to drop the temperature. If you have additional seahorses in the tank, be careful not to stress them out by lowering the temperature too rapidly or too drastically. If the temperature is colder or similar, float the bag for ten to fifteen minutes to enable the temperatures to equalize.
After this interval, unzip the bag and add one or two cupfuls of aquarium water to continue acclimating your seahorses. Allow another ten to fifteen minutes before releasing them.
As previously stated, pot belly seahorses are more temperature sensitive than many fish and cannot tolerate long periods of high temperature (e.g., over 30°C). Even tropical seahorses may get stressed if the temperature goes far over 30°C, particularly if oxygen levels are allowed to fall. Although aquarium heaters (if employed) will switch off when not required (for example, in hot weather), they will not chill the water. Chilling systems are available, but they are beyond reach for many enthusiasts. They may be necessary to sustain certain extremely sensitive temperate marine species, but the following methods should keep the temperature from creating difficulties for seahorses.
First and foremost, ensure that the filter is cleaned on a regular basis and that it is operating properly in the summer for optimal water oxygenation. Run an airstone for additional aeration to be sure. Warmer water stores less oxygen, and it is generally low oxygen content rather than temperature that creates issues.
Turn off illumination on very hot days to keep the temperature from rising too high, since even fluorescent bulbs generate heat. To aid cooling, direct wind over the water’s surface (keep hoods open and lids off or ajar). Replace the water with colder water, or in extreme circumstances, float a small bag of ice or a bottle of frozen water in the tank. Take caution if you do this; you don’t want to reduce the temperature too much or too soon since this would put the seahorses under even greater stress.
Diet & Feeding
Seahorses consume little shrimp and other crustaceans in the wild. The easiest approach to recreate this diet in the aquarium is to supply a variety of frozen meals such as brineshrimp, mysis, and plankton. Although baby seahorses may be given freshly hatched live brineshrimp at first, captive-reared seahorses are almost usually taught to eat frozen food before being sold. Frozen meals are preferred over fresh foods for adults since they are cleaner, pose less danger of illness, and have a bigger variety (plus, they are also much more economical). Feeding live items might make your seahorses picky and limit their diet.
Seahorses thrive on two to three little meals each day, although one feeding per day is plenty. Feed only as much as your seahorses can eat in around 5 minutes.
Because seahorses move slowly, they may have difficulty capturing food if it is being blown about by the filter. If your filter has a flow adjustment, you may want to turn it down while your seahorses feed. Alternatively, switch off filtration for a few minutes until they have finished eating.
Can I keep seahorses with other fish or invertebrates?
It is typically not suggested to maintain seahorses alongside other fish since the seahorses cannot compete for food. Furthermore, the majority of the commercially accessible marine species are tropical and demand water temperatures around 25°C. This is not beyond the temperature range permitted by potbelly seahorses, but it does need heating and close monitoring of the temperature. Only extremely tiny and slow-moving species should be introduced: certain bottom-dwelling fishes, such as blennies, are OK, but the options are restricted.
Some invertebrates may be kept safely with seahorses if a heater is employed. Starfish and snails are useful for algae removal, while little shrimps are excellent scavengers. Anemones and corals, on the other hand, are not suggested since they contain stinging cells that might damage the seahorses. Because of their sharp spines, urchins are likewise not suggested, although fanworms, sea apples, and sponges are. If invertebrates are to be retained, filtration may need to be improved: excellent biological filtration with a five-hour rotation is advised. Nitrates should also be maintained below 30ppm by doing minor frequent water changes. Protein skimming will assist manage nitrate buildup in bigger aquaria, but it is typically impractical to integrate protein skimming into tiny aquaria.
About other seahorse species
Other seahorse species found in Australian waters include the temperate Sydney seahorse (Hippocampus whitei) and the short-headed seahorse (Hippocampus breviceps), as well as the tropical Hippocampus kuda and Hippocambus barbouri. Because it is the most widely accessible wild-caught tropical seahorse, the oceanic seahorse (H. kuda) is one of the most well-known species. These four species are currently being raised in captivity, and although they are not as widely accessible as the potbellied seahorse, their availability should improve as more are developed.
Except for their temperature needs, all species require identical care. Sydney and short-headed seahorses need comparable temperatures as potbelly seahorses, but the other two demand a heated tank kept at roughly 25°C. Oceanic and Sydney seahorses may reach a maximum size of 15cm, although most reach approximately 12cm. The maximum size of Hippocampus barbouri is roughly 20cm, however, they are most usually observed around 15cm. The short-headed seahorse is the smallest of these species, measuring little more than 8cm.
Seahorse problems & diseases
Seahorses have extremely few illnesses. They are not susceptible to parasite illnesses like whitespot and velvet, which may be problematic in other saltwater fish. Seahorses, on the other hand, may succumb to bacterial illnesses if they are agitated or wounded. Most difficulties may be avoided by maintaining excellent water quality, and moderate antiseptics can be used as extra protection. If the illness is detected, use an antibiotic drug as soon as possible. An antibiotic bath (given outside the tank) may be required in extreme instances.
Infections of the pouch in male seahorses, gas bubble disorders, and fluke and worm infections are also sometimes reported. If you have any queries concerning your seahorse’s health, please contact us (you may use our email form here), consult our illness guide, or go to www.seahorse.org.