Yes, Hippocampus reidi and H. ingens are indeed close relatives. It may be helpful for the hobbyist to think of H. ingens as a giant version of its close cousin the Brazilian seahorse (H. reidi). The largest specimens of H. ingens can reach a length of 14 inches, about twice the size of large H. reidi. Hippocampus ingens is the only seahorse in the eastern Pacific, and it is closer genetically to the Atlantic H. reidi than any of its western Pacific counterparts (Dames, 2000). In fact, the two are believed to have diverged from a single ancestral species as a result of the formation of the Isthmus of Panama three million years ago (Lourie et al 1999).
The two species are very similar in their behavior and aquarium requirements, and both follow the same reproductive strategy, delivering huge broods of very small fry after a short two-week gestation period that must undergo a prolonged pelagic period of further development amidst the lipid-rich planktonic soup. This makes the offspring of both species very challenging to raise. Like H. reidi, H. ingens is believed to be monogamous in the wild, pairing up for the length of the breeding season at least (Dames, 2000). It is not known if the Pacific Giant forms permanent pair bonds, however, since they disperse and spend winters in the open ocean (Dames, 2000).
Aside from their difference in size, H. reidi is diurnal whereas H. ingens is reported to be nocturnal by nature. Specimens of H. ingens are often caught at the surface at night. As with H. comes, which is also thought to be nocturnal, there is speculation that the nocturnal behavior of H. ingens may be a recent behavior modification that resulted from heavy fishing pressure during the day (Dames 2000). H. ingens has been over harvested for use in Tradition Chinese Medicine (TCM), which favors large smooth-bodied seahorses such as ingens, and decimated by shrimp trawlers that take a heavy toll because the seahorses are attracted to shrimping grounds as a natural food source. Nocturnal behavior may thus have been selected for in H. ingens because the seahorses that are active by day are accidentally taken in trawls or deliberately collected by seahorse fishers for TCM and removed from the population.
If you contact me off list, Karen, I would be happy to send you additional information on both H. reidi and its gigantic relative. You can reach me at [email protected] any time.
I think the captive bred pipefish would probably do just fine with Ocean Rider seahorses, Karen. There is a far greater disease risk when dealing with wild-caught pipefish and many hobbyists keep the wild pipes with captive bred seahorses successfully.
Of course, wild caught pipefish should always be quarantined before introducing them to your seahorse tank. For example, here is the quarantine protocol for syngnatids followed by the Shedd Aquarium:
Shedd Aquarium Seahorse Quarantine Protocol
The following schedule sets out the basic quarantine schedule for seahorses entering the John G. Shedd Aquarium.
Chloroquine used to be part of the quarantine process but has been discontinued as a result of sensitivity.
Seahorse quarantine = 30 days
(1) Panacur In Artemia adults or nauplii: soak at 250mg Panacur /kg food and feed out as per normal food over 3 days. Artemia can be used to gut-load other food types if necessary. Start treatment on day 10 through 13 and repeat on day 20 through 23.
(2) Praziquantel bath at 10ppm for 3 hours or 1ppm for 24 hours on Day 29.
(3) Vaccine (Alpha-Dip 2100): dip at 1 part vaccine to 9 parts water for 20 to 30 secs on Day 7 and repeat on day 14.
(4) Diagnostic dip — Osmotic (freshwater) dip on Day 30.
(5) DHADC Selco as an addition to normal food. Soak prior to feeding as per label instructions) on Days 1 through 7.
If the captive bred pipefish from Western Australia are not raised at a high-health aquaculture facility, then it would probably be prudent to quarantine them as well.
Best wishes with all your fishes, Karen!