Seahorse Tank Mates

Although we suggest Seahorse are kept in ‘species only’ tanks or systems, this is not to everyone’s choice and we are asked regularly about tank mates for seahorses. Seahorses however are not Reef fish. We have compiled a brief list of only those Fish species, Invertebrates and Algae that are appropriate for Seahorse tanks and that we feel pose the least risk to seahorses. There is a fair amount of choice on the list, to keep your tank interesting and safe, from what we have described as Safe Tank Mates.
Please be aware there is always the exception to the norm, and some fish may occasionally display differently if mating or are threatened.
However, placing any other fish or algae in with captive-bred seahorse may always pose a risk at a microscopic pathogen level that is not visible by normal means. Placing any of these often wild caught tank mates into a seahorse tank is therefore at your own risk.
What the list means
0 = These species pose the least amount of threat to Seahorses. Competition for food is low, the fish are in general benthic (bottom dwelling) and peaceful. The Algae do not sting, although can release sticky substances when cropped and when stressed due to ‘a sexual’ reproduction.
1 = These species are still deemed to be safe, although there may be some competition for food. The fish have moved up into the water column slightly to feed. These fish are not fast swimmers nor are they aggressive, they are in general considered safe.
Not all these species are suitable for bare bottomed tanks, due to their preferred habitats.
LF = Live Food, some fish species have specific diets, such as Mandarins and require Live Foods.
RS = Reef Safe
The species on this list, although compatible with Seahorses are not necessarily compatible with one another, and as such should not be kept in the same aquarium.  Check them out fully first.
This list is not fully comprehensive and we would always suggest undertaking your own in-depth research. Fish or invertebrates that are not on this list can pose a greater threat 2+ or significant risk a 3 or 4 to your seahorses and their introduction to a seahorse tank should be dealt with a much greater degree of caution. They should be fully researched prior to purchase and tank placement and then carefully watched thereafter.
None of these Tank Mates on the list are deemed to be safe with H.zosterae. Please see the separate list for H.zosterae. If you are unsure, please ask.
Corals and Polyps  – Cnidarian (phylum)
Corals and Polyps have not been included on this list as the majority of the seahorses available for sale to aquarists, do not live on Coral Reefs, so these animals do not form part of their natural environment, they don’t choose to live around these animals so why put them in your tank? who benefits? They are also not included due to potential damage to seahorses skin from their ‘stinging’ or ‘burning’ tentacles – ‘cnidae’, and ‘chemical emitions’, even though many are night-time feeders with tentacles only coming out to feed, they are still a potential hazard and it is extremely difficult to correctly differentiate between species. If it stings you it will sting your seahorse, they too have skin not scales.
The phylum Cnidaria (and all subphyla or classes – Anthozoa, Cuboza, Hydrozoa, Scyphozoa, Staurozoa) have stinging cells – nematocysts, and can also give off a toxic mucus. Cnidarians include Jellyfish, Corals, Anemones, Hydroids, Gorgonians (Sea Fans, Sea Pens), Mushroom Corals (plate corals) are all of the phylum cnidarians and are related to jellyfish, hence the stinging cells  – nematocysts and their means of reproduction.
Stinging Cnidarians are:
Anthozoa (sea anemones, corals, sea pens, whips, gorgonians)
Cuboza ( box jellyfish)
Hydrozoa (hydrozoans – hydroids)
Scyphozoa (jellyfish)
Stauroza (stalked jellyfish).
Fish Species List
Striped Mandarin – 0                                              (Synchiropus splendidus)  LF         RS
Spotted Mandarin – 0                                             (Synchiropus picturatus)    LF         RS
Red Scooter Bleeny/Mandarin – 1                       (Synchiropus stellatus)       LF           RS
Scooter Mandarin  (Scooter Bleeny) – 1 (Ocellated Dragonet)                      LF           RS
(live rock, sand and colony of copepods)
Banghai Cardinal – 1                                             (Pterapogon kauderni)                   RS
Spotted/Pyjama Cardinal – 1                                (Sphaeramia nematoptera)             RS
Yellow/Orange-striped Cardinal – 1                    (Apogen cyanosoma)                        RS
Long Spine or Blue streak (strike) Cardinal – 1            (Apogon leptacanthus)
(like hidings places, best in groups, can be nocturnal, Pyjama cardinal may eat shrimp).
Barnacle Bleeny – 1                                                (Acanthemblemaria sp.)
Black Sailfin Bleeny – 1                              (Astrosalarias fuscus)                                RS
(likes rockwork)
Firefish – 1                                                    (Nemateleotris magnifica)                      RS
Scissortail – 1                                                          (Ptereleotris evides)                     RS
Zebra-banded Dartfish – 1                                    (Ptereleotris zebra)                        RS
(jump if startled, likes hidings places and sand for burrowing).
Court Jester Goby – 1                                             (Amblygobius rainfordi)                 RS
Black Clown Goby -1                                              (Gobiodon acicularis)                     RS
Green Clown Goby – 1                               (Gobiodon atrangulatus)                            RS
Catalina Goby – 1                                        (Lythrypnus dalli)                                      RS
Black barred Convict Goby – 1                  (Priolepis nocturna)                                    RS
(like sand and rock)
Jaw Fish
Pearly/Yellowhead Jawfish – 1                 (Opistognathus aurifrons)                            RS
(like hiding places and sand for burrowing)
Janss’ Pipefish – 1                                     (Doryrhamphus janssi)                             RS
Multibanded Pipefish – 1                           (Doryrhampus multiannulatus Sp             RS
Dragonface Pipefish – 1                            (Corythoichthys haematopterus)              RS
(likes rock and sand, best kept with Seahorses only, no other fish – expert level)
Sea Stars – Sand Sifting – 0                                 (Astropecten polycanthus)             RS
(Eat detritus, uneaten food, may need feeding, nocturna, not to be kept with Harlequin Shrimpl)
Sexy Shrimp – 0                                                                   (Thor amboinensis)
Pacific White (legged) Shrimp or Feeder Shrimp – 0              (Penaeus vannamei)
a saltwater shrimp – not to be confused with Glass/Ghost shrimps that can be freshwater.
Harlequin Shrimp – 0                                                                     (Hymenocera elegans)
(Harlequins and Starfish, do not make good tank mates, as Harlequin eat Starfish).
Fan Worms – 0
(Feather dusters) – polychaetes related to clam worms
Macro algae
Chaetomorpha (Green hair macroalgae) – 0
Caulaerpa prolifera (macroalgae) – 0
Botryocledia (Red grape algae) – 0
(be careful with the macro algae if they go ‘sexual’ and when cropping)
Vascular Plant
Sea grass (Eel grass) zostera marina- 0
Tank Mates List for H.zosterae only.
Small Mysid species
Bahai Mysis = 0                                                                                           LF
(Species native to Florida, natural diet of H.zosterae).
Macro Algae
Chaetomorpha – 0
Calerpa prolifera – 0
(be careful with the macro algae if they go ‘sexual’ and when cropping)
Vascular Plant
Sea grass – 0
This list has been complied from our own experiences as Seahorse keepers and Breeders along with the aid of other website information, plus much of our own research and time.
Please DO NOT USE or PURCHASE or STOCK Marine Green Algae (seaweed) Caulerpa Taxofolia and Caulerpa racemosa in your marine Aquarium. They are invasive non-native species. If you do have them dispose of them responsibly and correctly including all rock attachments – kill by freezing, chlorine, burning. Dispose in landfill, not down the drain. (IUCN invasive Species Specialist Group).

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