Wild Betta Fighting Fish Species in Thailand and Other Southeast Asian
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R EVIEW ARTICLE doi: 10.2306/scienceasia1513-1874.2020.064 Wild Betta fighting fish species in Thailand and other Southeast Asian countries Bhinyo Panijpana,+,∗, Namkang Sriwattanarothaib,+, Parames Laosinchaib a Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400 Thailand b Institute for Innovative Learning, Mahidol University, Nakhon Pathom 73170 Thailand ∗Corresponding author, e-mail: [email protected], + B. P.and N. S. are co-first authors Received 31 Jul 2020 Accepted 7 Aug 2020 ABSTRACT: This review updates what is known about Betta fish species in Thailand and Southeast Asian countries. The text is made easy to read for an uninitiated audience. It covers wild nest-builders, wild mouthbrooders, their appearance, distribution, and habitats. A section on domesticated fish is included for the general public. Details for more serious readership can be found in photos, maps, a table, and a diagram. DNA analyses for species differentiation leading to a phylogenetic tree and ancestral relationships are discussed. KEYWORDS: Betta spp., fighting fish, mouthbrooder, bubble-nest builder, species distribution, fish molecular taxonomy INTRODUCTION sometimes produce spectacular outcomes. Our group did the DNA work at the Canadian Ichthyologists know that many species of fish fight Centre for DNA barcoding, Guelph, Canada proving with their kinds and others to protect their territo- that wild B. splendens and most of the farmed nest- ries [1–3], but the name fighting fish appears to be builders shown here have basically the same bar- mainly attributed to a member of Betta genus, the coding sequences [7]. Our review of 2010 in this Siamese fighting fish, Betta splendens Regan, 1910. journal was published after the fact. It has been declared “the national aquatic animal” in Naturally, fighters derived mainly from B. splen- 2019 by The National Legislative Assembly of Thai- dens are also produced nowadays but not as many land (NLA). This formal declaration of the fish by as the ornamental ones described above (Fig. 1). the Thai Government may lead to better livelihood The fighter has a stout body, short fins, and sharp for smaller farmers and even high-volume exporters. teeth. Their trained endurance can cause some Mahidol University delegates had contributed sig- of them to fight to the death from injuries in nificant data, especially DNA analysis, during the gambling dens [8, 9]. Fighters are generally very three discussion sessions prior to the NLA historical hardy and not susceptible to pathogens. However, announcement. in general, both farm-bred and wild fish can be Before we describe wild Betta fish, we have to infected by parasites, bacteria, and other pathogenic address the domesticated ones first. agents [10–12]. DOMESTICATED BETTA FISH NEST BUILDERS AND MOUTHBROODERS Most people are familiar with domesticated (not In Betta fish, there are two separate modes of pater- wild-caught) fish bred by farmers and sold in the nal care for fertilized eggs and young fry [13–15]. market for fish lovers both locally and abroad with The nest-building male parent builds a raft of sticky high volumes. These fish mainly bred from wild bubbles shaped like a 3D convex lens, called a nest, B. splendens are desired mostly for their attractive on the water surface or underneath the aquatic plant appearance, body color and iridescence, fin shape leaves, to deposit newly fertilized eggs into each and color pattern, and body size [4–6] (see some bubble to take atmospheric oxygen [16–18]. Once domesticated Betta fish in Fig. 1). These are prod- the eggs hatch, the male parent would try to retrieve ucts of careful and diligent breeders from overseas some of the falling fry back into the nest [19, 20]. and in Thailand using mainly Mendelian genetics. Bubble-nest builders prefer stagnant waters [21]. These efforts often yield hit-and-miss results, but The mouthbrooding male takes fertilized eggs www.scienceasia.org 2 ScienceAsia 46 (2020) (A) (B) (C) (D) (E) (F) Fig. 1 Examples of domesticated Betta splendens sold in the market nowadays: (A) tricolor crown-tail fish possibly emblematic of flags of Thailand, France, the Netherlands etc.; (B) butterfly halfmoon; (C) veil tail or Pla Kat Jeen; (D) giant Betta (Jumbo); (E) Dumbo short fin; (F) fighter or Pla Kat Mor. The pictures are not of the same scale. to incubate in the mouth until the hatching stage. water with low oxygen content [25]: some can Even then, the male parent still keeps their young even survive in water with near-zero dissolved oxy- fry in the mouth for a while before releasing them gen. They can gulp air to put molecular oxy- to swim freely. Brooders prefer running waters, e.g. gen into the labyrinth organ inside the head re- near waterfalls [22, 23]. The male nester parent gion. Their distribution in Thailand is shown in uses the mouth to retrieve fertilized eggs and young Figs.2 and3 The nest builders occupy mainly the hatchlings when it feels danger [17]. They both thus north and central plains, the upper south, and the use their mouths in caring for their offspring. As can west (B. splendens); the northeast (B. smaragdina be seen later, they can evolve from one paternal care Ladiges, 1972); the eastern region (B. siamorientalis type to the other [15, 24]. Kowasupat, Panijpan, Ruenwongsa & Jeenthong, Betta females do not become pregnant after 2012); the upper and lower southern peninsu- viewing desirable males. They simply produce more lar Thailand (B. imbellis Ladiges, 1975); and the eggs that swell the ovary. Fertilization by male west of Bangkok, Samut Sakhon Province, and sperm occurs outside the female body when eggs are Samut Prakan Province (B. mahachaiensis Kowa- released. supat, Panijpan, Ruenwongsa & Sriwattanarothai, All these freshwater Betta fish have a com- 2012) [21–23, 26–29]. Recently, large populations mon feature that is important for their survival in of B. smaragdina were unexpectedly found in the www.scienceasia.org ScienceAsia 46 (2020) 3 Fig. 2 Distribution of selected nest-building Betta species in Thailand and neighboring countries. www.scienceasia.org 4 ScienceAsia 46 (2020) Fig. 3 Distribution of selected wild mouthbrooding Betta species in Thailand and other ASEAN countries. No brooders are found at latitudes above 14.5 degrees north. Wild nesters are also found in Eastern Malaysia and Kalimantan part of the Borneo Island. south region of Kanchanaburi Province [30]. B. simplex and B. mahachaiensis are subjected to The brooders are mainly found in the lower high-volume exports that will push them further into southern peninsular Thailand provinces (Fig. 3), in- the critically endangered species list [27, 32, 33]. cluding big islands, e.g. Samui and Pa Ngan [22, WILD BETTA FISH IN THAILAND 29, 31]. These fish are found in streams with run- ning water originating from waterfalls, which can Five wild-type nest-building fish in Thailand are be quite a distance away. Incidentally, Thailand very colorful when they, especially males, display has endemic species of the Betta genus, namely their full aggressive posture or stage courtship dis- the brooders B. simplex Kottelat, 1994, B. pallida plays [8, 34–36]. The body turns dark, fins are Schindler & Schmidt, 2004, and B. prima Kottelat, unfurled, and colors and color patterns of fins in- 1994, and the nest-builder B. mahachaiensis. Betta tensify. With the naked eye, some of their external prima is found in the eastern region of Thailand. body features of five nest-building Betta in Thailand that are sufficient for differentiating them from one www.scienceasia.org ScienceAsia 46 (2020) 5 Table 1 Comparative table showing, as seen through the naked eye, some external characters of five wild nest-building Betta species of Thailand that sufficiently differentiate one species from another. Betta species B. splendens B. imbellis B. siamorientalis B. mahachaiensis B. smaragdina Opercle Two parallel vertical Two parallel vertical Two parallel vertical Two to three parallel Multiple iridescent red bars iridescent bluish- red bars vertical iridescent yellowish-green to green bars bluish-green bars bluish-green plates or scales Caudal fin – Bluish-green strips – Bluish-green strips – Bluish-green strips – Dark strips fanning – Dark strips fanning fanning out from fanning out from fanning out from out from caudal pe- out from caudal pe- caudal peduncle caudal peduncle caudal peduncle duncle toward poste- duncle toward poste- toward posterior toward posterior toward posterior rior with bifurcation rior with bifurcation – No black dot – No black dot – No black dot – Presence of black – Presence of black – At least 50% of – Less than 20% of – Less than 20% of dots flanking stripes dots flanking stripes red area red area red area – With distal red – With distal red crescent and thin crescent and thin black edge black edge Anal fin At least 40% of red About 5% of red at About 5% of red at – Absence of red area – Absence of red area area distal tip distal tip – Blue interradial area – Blue interradial area Pelvic fin Red-brown to black Red-brown to black Red-brown to black Brown to black with Brown to black and and red from and red from and red from proxi- iridescent green to red from proximal proximal pelvic fin proximal pelvic fin mal pelvic fin base to bluish-green front pelvic fin base to the base to the white tip base to the white tip the white tip margin and white tip white tip (some populations having green to bluish-green front margin) Body scale and – Scale iridescence – Scale iridescence – Scale iridescence – Scale iridescence – Scale iridescence background not prominent prominent prominent very prominent prominent – Body background – Body background – Body background – Body background – Body background dark brown dark brown black black dark brown another are included in Table 1 and Fig.