One of the first things to consider is the species of seahorse you wish to keep as this will determine the type and size of tank setup
you will need to house your chosen species. Seahorses are definitely amongst some of the more specialised of marine fish to keep and
their tank requirements are quite different to those of most other marine fish and indeed differ amongst the various species of
seahorses themselves.
It is highly recommended to only buy captive-bred/raised seahorses. As well as helping with seahorse conservation, it also greatly reduces the risk of introducing bacterial diseases and parasites that can accompany wild-caught specimens. Wild-caught specimens can be very difficult to feed as generally they will only eat live foods and won't accept any type of frozen food. Although often done, it is not recommended to mix different species of seahorses within the same tank. Not only does this increase the risk of cross-breeding but each species carries its own range of parasites and pathogens and mixing species together can have detrimental effects. Although this is less likely with captive-bred specimens, it is still a possibility.
A temperate coldwater species that will need to be housed at a temperature of 18-20C.
H. abdominalis are far easier to identify compared with many other seahorses. The first thing you will notice is their body is much deeper than that of other large seahorses. They also have more trunk rings (12-13), tail rings (45-48), and dorsal fin rays (26-29).
The spines are small and rounded but those around the eye are quite prominent. The coronet is also low and triangular in shape, the male's pouch is very large and often coloured white with a yellow bordering.
As with all seahorse species, H. abdominalis' colouring is not permanent and may change based on surroundings, diet, stress, mood and possibly other factors. Generally speaking, they are brightly coloured in various shades of yellow (however, white and brown specimens are not uncommon), with dark markings over the body and alternating dark and light markings on the tail. Males generally have darker markings, longer tails, shorter snouts and are heavier looking whilst females have a much deeper keel by comparison.
As with the majority of seahorses once settled in and the right conditions met, a pair will initiate a regular breeding cycle. They have a gestation period of approximately 30 days and their fry are pelagic.
H. agustus' spines in general are well developed with either blunt or sharp tips, usually low around the neck region. They have double sharp tipped cheek spines and double spines below their eyes. They have 11 trunk rings, 33-34 tail rings, 18 dorsal fin rays and 16-17 pectoral fin rays. The coronet is medium height with 5 well developed sharp spines.
Colour again is changeable and varies from either white, orange or yellow with lighter patches. The body is often covered in a net-like pattern of fine brown lines and markings. Also the snout often has fine stripes and their spines have a brown band towards the tip.
H. barbouri have well developed spines.They usually have sharp eye spines and the first dorsal trunk spine is much longer than others and curved backwards. They have double cheek spines and double spines below their eyes. Their tail spines alternate in length (long, short, long, short) and in a regular pattern. The coronet is medium-high and will have five sharp spines protruding from it. They have 11 trunk rings, 34-35 tail rings, 16-22 dorsal fin rays. Their colours again changeable, typically ranging from white through pale yellow to pale brown, and may have some reddish-brown or pink spots and lines on the body. Snouts are quite often striped and have fine lines radiating from the eyes.
As with the majority of seahorses, once settled in and the right conditions met, a pair will initiate a regular breeding cycle. They have a gestation period of approximately 30 days and their fry are benthic.
H. breviceps' spines are irregularly developed; some very low, others very prominent rounded tubercles. They have 11 trunk rings, 40-43 tail rings, 20-21 dorsal fin rays and 14-15 pectoral fin rays. The coronet is generally well extended and can be either column or knob shaped. Some specimens also sport a mane of thick skin on the back of the head and neck region and mature males can have a very prominent brood pouch. Colour again is changeable and ranges from yellow - brown - purple with a reddish tint. They often have dark spots on their heads and striped tails.
H. comes' spines vary from stubby and blunt to well developed and quite sharp. They often have a dark band around them near the tip. They have a prominent sharp nose spine, double cheek spines and double spines below and sometimes also above the eye. They have 11 trunk rings and 35-36 tail rings, 18 dorsal fin rays and 17 pectoral fin rays. The coronet is small and quite low, with five distinct rounded stubs or spines. Colour is changeable and varies but commonly hues of yellow, black or silver, sometimes alternating between them. They have a mottled or blotched pattern on the body, striped banded tail although this may not always be visible in darker specimens. They may also have fine white lines radiating from around the eye.
As a side note it should also be mentioned that H. comes is mainly nocturnal and will generally hide when the lights are on.
H. kuda are a smooth seahorse with very low stubs instead of spines. They have a deep head, deep body and a thick snout, and will often have spots throughout their entire body. They have 11 trunk rings, 36 tail rings, 17-18 dorsal fin rays and 16 pectoral fin rays. The coronet is low to medium, rounded and overhanging at the back, often with a cup-like depression in the top and sometimes with broad flanges. Colours, again changeable, typically range from black to orangish yellows to pale yellows. Their colours are not permanent and can change based on surroundings, diet, stress, and mood, often totally black with a grainy texture, alternatively pale yellow or sandy cream with fairly large dark spots, especially females. Fry are pelagic.
Adult height is 20cm (8"), the recommended minimum tank size for a pair is 60 litres (13 gallons) plus an extra 30 litres (7 gallons) for each additional pair. A tropical species, water temperature should be maintained between 22-24C.
H. reidi are another smooth seahorse with very low rounded stubs instead of spines. They have a narrow body, usually no skin
appendages and a long thick snout. They have 11 trunk rings, 35 tail rings, 17 dorsal fin rays and 16 pectoral fin rays. The coronet
is low to medium, rounded and can be quite large and convoluted. Colour varies from black, brown, Orange, bright reds, bright yellows
and pale yellows. Again their colors are not permanent and can change based on surroundings, diet, stress, and mood. They are often
profusely decorated with many small dark spots and numerous tiny white dots especially on their tails. They often have paler sections
crossing their backs' surfaces and also fine lines radiating from around the eyes. Fry are pelagic.
With an adult height of just 4cm (1.5"), due to this size and the fact that they must be fed exclusively on live baby brine shrimp and/or copepods, selecting the right sized tank is absolutely crucial. The Dwarf Seahorse does best in groups of 4 or more and the recommend ratio is to keep small herds of up to 6 specimens in a 20 litre (5 gallon) tank. Advanced aquarists may find success in larger tanks but generally speaking this species prefers to hitch and feed on passing live food rather than actively go hunting for it, so you will find a smaller tank size will help to concentrate the food. If keeping 10 or more Dwarf Seahorses then a 40 litre (9 gallons) tank should be used instead. A tropical species, water temperature should be maintained between 22-24C.
H. zosterae are a very small seahorse with low or stub like spines. They have a short snout about 1/3 of the head length and their skin is quite often covered in tiny warts. They have either 9 or 10 trunk rings and 31 or 32 tail rings, 12 dorsal fin rays and 11 or 12 pectoral fin rays. The coronet is high, columnar or pillar like and has no spines or projections. Colours are changeable but will typically range from black, brown, grey, green, yellow, orange, red, and can often have white markings like splashes of paint. Alternatively some lighter specimens have dark splashes, commonly mottled brown to white, sometimes yellow, green or black and less commonly multi-colored yellow and black, with mottling variable from distinct to absent, polka-dotted and pinto. Colours are not permanent and may change based on their surroundings, diet, stress, mood and possibly other factors.
Very few tank mates are compatible with this species. Only tiny hermit crabs, Hawaii red shrimp, sea hares, snails and small pipefish. However it should be noted that the pipefish will generally out compete them for the food so they will need to be monitored carefully. Also great consideration must be given to their tank setup. It is recommended to use external filters containing foam sponges for biological filtration with this particular species. Ideally the tank should be kept as clean and clear as possible - fake blunt-edged plastic plants are recommended and used as hitching material instead of live algae, as these as well as the rock and sand can often contain hitchhikers such as hydroids and Aiptasia, plus the toxins released during the crashing of these macroalgae can often be fatal. Hair algae is another high risk issue for these little fellows as they can often get trapped and die from stress whilst trying to escape. Although it's quite commonly found in a lot of seahorse tanks, with regards to this species it should be removed immediately.
If live-rock, sand or algae are to be used, then it is absolutely vital that they are quarantined and screened very carefully for any type of stinging animals which can be aggressive and highly dangerous towards this delicate little seahorse.
Tank-mates also need to be slow and this is mainly due to seahorses not being the quickest of feeders. They will often gaze at a piece of food for some time before deciding that it is actually edible. Any quick tank-mates will usually end up eating all the food first!
As seahorses are vertical swimmers, when choosing your tank I would suggest that the height is to be considered far more important
than the length as generally speaking most species will require a tank with a height of at least three times their adult size. The
seahorse tank setup can be as simple or as technical as any other marine-based system and this will depend largely on other tank
inhabitants. Sumps can be incorporated into the setup and have all the usual benefits associated with them. However if breeding
seahorses are to be kept then sump filter systems are not recommended due to the risk of fry being swept away.
Seahorses will consume large volumes of high-fat, high-protein foods. They also have a very short and inefficient digestive system and are notoriously messy eaters so an efficient clean up crew and good filtration is absolutely vital to maintaining a healthy tank. Live rock/sand and macroalgae together with regular water changes is by far the most commonly used setup and what I would recommend as the main form of bio-filtration. There are however, many seahorse tanks which run quite successfully using just canister or "hang on back" (HOB) filters, H. zosterae for example are recommended to be kept using these methods.
(As a side note I would also highly recommend quarantining and carefully examining all live rock for hitchhikers such as rogue crabs and Aiptasia before putting it into a seahorse tank. It is not uncommon for seahorses to be attacked by carnivorous crabs or stung by Aiptasia and removing these later on can be a difficult task).
Peaceful, slow swimmers, seahorses do not like or do well in strong currents and this must be considered when aquascaping live rock within the tank. Seahorses also require a habitat with a different decor to that of most marine fish tanks - a wall of live rock is not the kind of home your seahorses are going to appreciate! They prefer a large open space with vertical hitching posts to anchor onto with their prehensile tails. As long as their tails can wrap around them, hitching posts can be a variety of shapes and sizes and the more variety there is the happier the seahorses will be.
What is important is balancing the amount of live rock with the open space needed. Tonga branch is one way of creating both hitching posts and providing live rock. Most seahorses enjoy Tonga branch and other types of live rock to poke around in looking for naturally occurring crustaceans to eat. Ideally the rocks should be placed low with large gaps between them to allow the slow moving water column to pass through freely - small, low volume powerheads fitted with diffusers are ideal to create gentle circulation within and around the rockwork. Small air pumps with open ended airlines are also widely used - they not only create good water movement but are also excellent for oxygenating the aquarium and can help to maintain pH levels in the absence of a skimmer.
Air-stones and wooden diffuser-blocks should be avoided where seahorses are concerned. It is believed that the fine bubbles produced by these items could be a possible cause of Gas Bubble Disease (GBD) often found in captive seahorses. Ideally water movement should be kept to a gentle flow throughout the whole tank, just enough to keep foods suspended in the water column and to avoid any dead spots.
Macroalgae are widely used and recommended in seahorse tanks. Not only do they play a large role in the filtration processes of nitrate reduction but they also create an excellent breeding ground for desirable macro life such as copepods which are a nutritious and valuable live food source. It also allows the seahorses to create territories within the tank when more than a single pair are housed together. It is often desirable to have a range of different macroalgae within the tank and regular pruning will help to keep these healthy and under control, However it is important to monitor macroalgae very carefully as due to the lighting cycle they receive most can turn asexual and crash. This will cause the release of toxins back into the water column and should be avoided by removing the algae beforehand. It is usually apparent when this is about to happen by a yellowing or paleness of the macroalgae just prior to it crashing.
Ultra-violet (UV) sterilisers are also highly recommended as part of a seahorse tank's filtration system and are used for the removal of parasites/pathogens from the water column.
Protein skimming is a highly debated topic amongst seahorse keepers and is really a matter of personal choice. Opinions vary greatly on whether skimmers should or should not be used on a seahorse tank. Although unproven, it is claimed that skimming could be a possible cause of GBD found in seahorses. I have used skimmers on all my seahorse tanks, past and present, and have not experienced any ill-effects from doing so. In my opinion, if set up correctly, the benefits from using one strongly outweigh the possible risks involved.
As always the tank should be setup and fully cycled before the introduction of any livestock.
In their natural habitat seahorses feed continuously throughout the daylight hours. They can consume vast amounts of small crustaceans and other larval organisms (collectively called "zooplankton"). This means in the wild they are free to select prey items from a lipid and protein rich planktonic soup consisting of countless copepods, mysis, amphipods, isopods, shrimps and the larval stages of larger crustaceans. Trying to replicate the quality and quantity of this natural diet is the seahorse keeper's greatest challenge.
In captivity seahorses should be fed regularly on heavily enriched frozen meaty foods such as mysis, daphnia and Pacific krill,
preferably a mixture of them all together so as to increase the overall variety. Enrichment products such as Selcon are excellent as
they contain high levels of highly unsaturated fatty acids (HUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and
should be used constantly as part of their feeding regime.
When feeding, it is also preferred to offer foods which are either naturally sourced or produced in a marine environment. Marine species contain far more HUFAs than freshwater species which either lack them or have them in the wrong concentrations. Although it is often recommended by the local fish shop (LFS) selling seahorses, live or frozen brine shrimp, even when enriched, is very low in nutritional value and should never be fed as a main diet (excluding H. zosterae).
However, brine shrimp is often used mixed together with other foods to increase the overall variety given to the seahorse. It is highly desirable to have a good healthy population of copepods and amphipods within the tank as this is by far the most nutritious food source available for any captive seahorse. Live ghost/river shrimp are also commonly used and generally well accepted by larger seahorses. These shrimp can be gut loaded (fed) with such things as spirulina, HUFA enriched baby brine shrimp (BBS), cyclops and quality flake foods prior to feeding to your seahorses.
I use either T5 or T8 fluorescent lighting and wouldn't recommend the use of metal halides as this will make it increasingly difficult to control the overall aquarium temperature and increases the likelihood of needing to use a chiller.
I would always recommend trying to run the aquarium temperature at the lower end of the species' temperature range as this is known to slow down and help reduce the risk of bacterial and parasitic infections. Cooling fans and chillers can be used to maintain the desired temperature.
This article has been written and is intended as a general guide only. Seahorse keeping is a vast subject and I would highly recommend further indepth research into any chosen species before making a purchase.