In nature, things are not always what they seem.🔍 Take the Paradise Fishes for instance. These fishes are found in freshwater systems, and in Hong Kong two species were considered to occur: the common Chinese paradise fish, 𝘔𝘢𝘤𝘳𝘰𝘱𝘰𝘥𝘶𝘴 𝘰𝘱𝘦𝘳𝘤𝘶𝘭𝘢𝘳𝘪𝘴, and the black paradise fish, 𝘔𝘢𝘤𝘳𝘰𝘱𝘰𝘥𝘶𝘴 𝘤𝘰𝘯𝘤𝘰𝘭𝘰𝘳. Things took a different turn, however, when in 2002, two German scientists, Jörg Freyhof and Fabian Heder, after examining specimens collected at Sha Lo Tung realized that the specimens considered as 𝘔. 𝘤𝘰𝘯𝘤𝘰𝘭𝘰𝘳 were in fact a new species endemic to Hong Kong😮, which they described and logically named 𝘔𝘢𝘤𝘳𝘰𝘱𝘰𝘥𝘶𝘴 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 (Freyhof & Herder, 2002). As a result, previous records of 𝘔. 𝘤𝘰𝘯𝘤𝘰𝘭𝘰𝘳 were out as all turned out to be 𝘔. 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴, which is also the only freshwater fish species named after Hong Kong! 👏
The new species received a common name as the Hong Kong Paradise Fish. But here again, things changed as the species lost its endemic status when populations of 𝘔. 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 were discovered soon after 200 km East of Hong Kong in Guangdong and later on even further in Fujian. A good reminder of how little we know about species diversity and their distributions 😢, even for relatively large organisms as these fishes measure 6 cm; which in relation to many other organisms is quite large.
But what are the differences between 𝘔. 𝘤𝘰𝘯𝘤𝘰𝘭𝘰𝘳 and 𝘔. 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴?🤔Well, they look very similar but can still be separated by small differences in their coloration of fins. For instance, 𝘔. 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 has a white pelvic fin ray (fins that are extending outwards), while it is red in 𝘔. 𝘤𝘰𝘯𝘤𝘰𝘭𝘰𝘳 . Another more conspicuous difference is that 𝘔. 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 has a black spot on the operculum (gill plate), which 𝘔. 𝘤𝘰𝘯𝘤𝘰𝘭𝘰𝘳 doesn’t.
Individuals prey on insect larvae, invertebrates, and fish fry. Like other Paradise Fish, males 𝘔. 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 are territorially aggressive, and this behaviour becomes more pronounced during reproductive periods. In addition, 𝘔. 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 are bubble nesters, meaning that individuals release floating masses of bubbles on the water surface, forming bubble nests. The bubbles are composed of oral secretion, saliva, and sometimes aquatic plants.💭 Once the nest is complete, the male will entice the female to lay her eggs by displaying his elongated fins to her. When the female approves of his hard work, it will swim under the nest as a signal of willingness to mate. Then they will spawn under the nest, releasing eggs and sperms into the water. Eggs contain globules of oil and are thus lighter than water, so after fertilization, the fertilized eggs float upwards. The male gathers the fertilized eggs into the bubble nest. After spawning, the male will violently attack other fish (or even his mate!) that might approach the newly fertilized eggs or hatched fry to prevent them from being eaten. A responsible father, isn’t it? 👨🏻
Regrettably, those small and colourful fishes suffer severe threats such as the degradation of their habitat or their capture for the aquarium hobby trade. Unfortunately, while 𝘔𝘢𝘤𝘳𝘰𝘱𝘰𝘥𝘶𝘴 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 meets the criteria to be listed as Endangered under the IUCN Red List⚠️, they are not included in the Protection of Endangered Species Ordinance in Hong Kong. It is thus important for these misunderstood fishes to get their local “paradise” protected before no more bubbling could be seen in Hong Kong waters.🌌
Without bubbles but still with interest, you could come and see a specimen of 𝘔. 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 at the HKBM.
Text: Alan Fok
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