These alien catfish were seen at the very same forest pool inhabited by two native congeners (Clarias leiacanthus and Clarias nieuhofii) that are regarded as locally endangered (Lim, 2013). The stream where the pool was located flows into the Nee Soon swamp-forest, an area where most of Singapore’s native freshwater fishes occur. The alien catfish were most likely unused bait released by anglers, or they could also have been deliberately liberated for religious reasons.

First found in 2006, this introduced species has hitherto been found only around the northeastern and western part of Singapore Island (Tan & Clements, 2011; Tan & Low, 2011). Several empty shells were also found at Sungei Tengah Road in 2012 (a locality not noted by Tan & Low, 2011). This is the first observation of this West African species in the southern part of the island. The figured individual was found in a recently landscaped garden and probably hitchhiked to the location with the plants, but it remains unknown if a viable population has established in the area.

The presence of Limicolaria flammea in Singapore was first documented by Tan & Clements in 2011 with records from Tuas, Lentor, Yio Chu Kang, Seletar Aerospace Park and Seletar Farmway. This African snail was later found at Braddell Heights, Yishun, Chong Kuo Road (Tan & Low, 2011) and along Pandan Canal at Clementi (Tan, 2013). The present observations add Upper Seletar Reservoir Park to the known localities of this alien species in Singapore

Opinions and declarations Rendered by the International Commission on Zoological Nomenclature

Opinions and declarations Rendered by the International Commission on Zoological Nomenclature

Demoiselles (genus Neopomacentrus) are common reef fishes in Singapore waters. They tend to hover in large aggregations in the water column, feeding on zooplankton. The two congeners featured here are distinguished by their distinct colour pattern. Neopomacentrus filamentosus has whitish caudal fin with a black margin on each lobe, and a black spot at the base of its pectoral fin. Neopomacentrus bankieri has its caudal fin, caudal peduncle and rear part of the dorsal fin yellow. (Allen & Erdmann, 2012: 606-607)

Tytthosoceros lizardensis was first recorded in Singapore by Bolaños et al. (2016). This is the second recorded aggregation of this species in Singapore. The first was reported in October 2015 at a seagrass meadow within the Seringat-Kias lagoon (Ong et al., 2015). Mating and abundance of food source are likely reasons for such aggregating behaviour. However, in this present sighting, none of these flatworms displayed mating behaviour. It is not known why some of the flatworms were damaged.