Photographed individuals from the Togean Archipelago, Indonesia were originally identified as Hippocampus satomiae Lourie and Kuiter 2008. They were later revealed as the Walea Soft Coral Pygmy Seahorse (H. waleananus) based on a single specimen from Walea Islands in the Togean Archipelago by Gomon and Kuiter 2009, citing differences in tail lengths, tail ring counts, and dorsal fin rays. Lourie et al. 2016 subsequently determined H. waleananus as a synonym of H. satomiae, given their lack of differences aside from those mentioned by Gomon and Kuiter (2009), and the fact that the locality of H. waleananus is completely within the distribution of H. satomiae. However, Short et al. 2018 have recognized H. waleananus as a distinct species based on its morphological characteristics, body ornamentations, host association, and behavior.

The Walea Soft Coral Pygmy Seahorse (Hippocampus waleananus) occurs in the Western Central Pacific and is only known from the Togean Archipelago in Central Sulawesi, Indonesia. It has been found in obligate association with Nephthea soft corals at depths of 5–20 m. This seahorse is primarily threatened by habitat loss and degradation due to blast and poison fishing, coral mining, and climate change, and it is inferred that its habitat quality and/or extent has undergone a continuing decline. There are no population size estimates available for this seahorse to date, but anecdotal evidence suggests that there has been an observed reduction in the number of mature individuals. This seahorse nearly meets the criteria for Endangered under criterion B, given an extent of occurrence (EOO) of <5,000 km², inferred continuing decline in habitat quality and/or extent, and no evidence of extreme fluctuations. However, it does meet the conditions for Critically Endangered under criterion A as it is suspected to have undergone a past population reduction of  >80% over 10 years based on reduction in number of mature individuals and a decline in habitat quality, and this reduction is suspected to continue over the next 10 years. Therefore, the Walea Soft Coral Pygmy Seahorse is assessed as Critically Endangered under A2bc+3bc.

The Walea Soft Coral Pygmy Seahorse occurs in the Western Central Pacific. It is only known from the Togean Archipelago in Central Sulawesi, Indonesia (Gomon and Kuiter 2009).

There have been no dedicated surveys or population estimates for the Walea Soft Coral Pygmy Seahorse to date.

Guests and owner of the Walea Dive Resort reportedly did not see the seahorse for at least 15 months from the beginning of 2012 to mid-2013 after a period of higher-than-usual sea temperatures, despite dives being done three times daily, every day of the week (R. Smith, unpub. data 2023). Other pygmy seahorses had supposedly moved to deeper habitats then returned, but this did not seem to be case with the Walea Soft Coral Pygmy Seahorse. It is suspected that the Walea Soft Coral Pygmy Seahorse has undergone a past and ongoing population reduction of >80% over 10 years, given the continuing decline in its habitat quality and the lack of observations after the high temperature event.

The Walea Soft Coral Pygmy Seahorse is one of the smallest seahorse species with a length of 1.8 cm standard length based on a single specimen observed by Gomon and Kuiter 2009. It is found at depths of 5–20 m and it has been observed in obligate association with Nephthea soft corals (Gomon and Kuiter 2009). Little is known about its feeding, but it is likely similar to other Hippocampus species and feeds on small crustaceans such as copepods and amphipods (Kendrick and Hyndes 2005, Manning et al. 2019). It is ovoviviparous, with pregnancy occurring in males (Foster and Vincent 2004). Similar to other pygmy seahorses, brooding occurs in the trunk region without being enclosed in an external pouch structure (Gomon and Kuiter 2009). Its generation length is unknown, but is not expected to exceed 3 years as seahorses have an estimated lifespan of 1–5 years, with smaller seahorses being on the lower end of the range (Foster and Vincent 2004).

The Walea Soft Coral Pygmy Seahorse is primarily threatened by habitat degradation due to destructive fishing and temperature extremes caused by climate change. Coral reefs in the Togean Archipelago are threatened by destructive fishing practices (blast and poison fishing) and coral mining (Burke et al. 2002, Moore and Ndobe 2008, Yusuf and Moore 2020). Declines in live coral cover and condition in the Togean Archipelago have been observed between 1989 and 2015 (Yusuf and Moore 2020), and at least 60% of corals in the Togean Islands National Park have reportedly suffered mild to serious damage due to blast fishing (Ridwan and Haryati 2021).

Coral reefs within the country may also be affected by the more frequent and widespread bleaching events expected under future warming conditions (Burke et al. 2002, Wouthuyzen et al. 2018). Some bleaching in the Togean Archipelago has been observed in 2015, with almost 50% of the coral colonies surveyed exhibiting paler or abnormal coloration compared to past surveys (Yusuf and Moore 2020). However, the effect of climate change on the Nephthea soft corals that this seahorse associates with is unclear, given mixed results from past studies regarding the resilience of soft corals against ocean warming and acidification (Bramanti et al. 2013, Gabay et al. 2013, Inoue et al. 2013, Gabay et al. 2014, Gómez et al. 2015, Goulet et al. 2017, Januar et al. 2017, McCauley et al. 2018, Quintanilla et al. 2019). Diseases associated with warmer temperatures have also been observed in gorgonian coral populations globally, although reports from the Indo-Pacific region are relatively few in number (Sutherland et al. 2004, Weil et al. 2016).

Given the pressures affecting corals within this seahorse’s range, it is inferred that there is a continuing decline in its habitat quality and/or extent.

The Walea Soft Coral Pygmy Seahorse has not been recorded in trade. It is unlikely to be targeted for aquarium trade as its diminutive size and cryptic appearance can make it extremely challenging to find. It is also unlikely to be traded for traditional Chinese medicine as preference is commonly given to large, pale, and smooth seahorses (Vincent et al. 2011).

There are no species-specific management or conservation measures in place for the Walea Soft Coral Pygmy Seahorse. All Hippocampus species are listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which requires exports to be sustainably sourced and subject to regulations (Vincent et al. 2011). Exports of wild seahorses are also banned in Indonesia in response to the CITES Review of Significant Trade (Foster 2016). This seahorse occurs in at least one protected area (e.g. Togean Archipelago National Park) (UNEP-WCMC and IUCN 2022).

Further research is needed to determine population and habitat trends. Regulations on fishing practices and climate change mitigation are necessary for the conservation of this seahorse. Efforts to establish an ex situ insurance population and to bank genetic material should be considered.