Aquacult. Sci. 63（2），207－212（2015）

Note

Spawning and rearing of a porcupine puffer orbicularis (Diodontidae, ) in captivity

1 1 2,＊ Hiroyuki DOI , Toshiaki ISHIBASHI and Harumi SAKAI

Abstract: (Diodontidae, Tetraodontiformes) were spawned in captivity, the larvae being reared for more than 60 days, in the Shimonoseki Marine Science Museum Aquarium. Isolated epipelagic eggs, 2.2 mm in mean diameter, hatched two days after spawning. Hatched larvae were 3.5 mm in total length, the head and trunk being covered by a “vesicular dermal sac”. Fin rays were completed in 17 days after hatching at 7.6 mm TL, some rudimentary spines appearing on the dorsum. Spines had become unmovable in 39 days after hatching at 20.8 mm TL. Growth rates from hatching to 8 days and thereafter from 9 days were different, growth regression equations between TL (y) and days after hatching (x) being y = 0.052x + 3.518 and y = 0.295x + 2.046, respectively.

Key words: Porcupine puffer; Spawning; Development; Growth

Porcupine puffers of the family Diodontidae Randall) (Aizawa and Doiuchi 2013; Froese and include seven genera, 17 and two sub- Pauly 2014). species, variously distributed throughout tem- The present report details the first observa- perate to tropical seas worldwide (Froese and tions of spawning, eggs and larval development Pauly 2014). Four genera, including seven for more than 60 days of Cy. orbicularis held species, have been recorded from Japanese in the Shimonoseki Marine Science Museum waters (Aizawa and Doiuchi 2013). A few Aquarium. Although the observations were not reports on life history have indicated that iso- especially detailed, it was clear that this species lated epipelagic eggs are spawned, juveniles spawns isolated epipelagic eggs just as other and young migrating to open pelagic diodontids (Fujita and Matsuura 2014), the waters (Nishimura 1960; Fujita 1962; Leis 1978; larval and juvenile development being similar to Sakamoto and Suzuki 1978; Fujita and Matsuura that of holacanthus Linnaeus, described 2014), in contrast to tetraodontid puffers that by Sakamoto and Suzuki (1978). spawn demersal adhesive eggs (Fujita 1962; Sakamoto and Suzuki 1978; Fujita and Matsuura Materials and Methods 2014). Two of the three known species of the Wild-caught adults of Cy. orbicularis from Cyclichthys have been recorded from Japan, Cy. unknown locality, a female ca. 20 cm in stan- orbicularis (Bloch) and Cy. spilostylus (Leis and dard length (SL) and a male ca. 15 cm SL,

Received 19 November 2014; Accepted 6 February 2015. 1 Shimonoseki Marine Science Museum “Kaikyokan”, Shimonoseki Academy of Marine Science, Shimonoseki, Yamaguchi 750-0036, Japan. 2 Department of Applied Aquabiology, National Fisheries University, Shimonoseki, Yamaguchi 759-6595, Japan. ＊Corresponding author: Tel, (+81) 286-5111; Fax, (+81) 286-7435; Email, sakaih@-u.ac.jp (H. Sakai). 208 H. Doi, T. Ishibashi and H. Sakai were purchased from a fish dealer and main- de Procé), Tetrosomus concatenatus (Bloch), tained in a closed circulating-filtering exhibition Lactoria diaphana (Bloch and Schneider), aquarium of 1.1 m3 (0.75×1.00×1.50 m) with trigonus (Linnaeus), Chilomycterus a large imitation coral rock on the coral sand antillarum (Jordan and Rutter) and Ch. anten- bottom, in the Shimonoseki Marine Science natus (Cuvier), all Tetraodontiformes, were Museum from August 2001. Water tempera- maintained in the same aquarium, being fed ture was kept at 25℃ and subject to cyclic 12 three times weekly with processed giant tiger h light and dark periods (Fig. 1A). Two indi- prawns and Manila clams. viduals of Arothron nigropunctatus (Bloch and Although sexing of adult Cy. orbicularis is Schneider) and each one of A. manilensis (Marion usually very difficult, the belly of the female became swollen several days before spawn- ing. Both adults nestled close to each other on the bottom the day before spawning (Fig. 1B). Although the actual spawning behavior was not observed, the female belly shrank after spawning. Spawned eggs were found on five separate occasions in May 21 (18 : 00), June 22 (9 : 00), August 27 (16 : 00), September 26 (9 : 00 and 11 : 30) and November 6 (12 : 00), 2004. The eggs spawned in May and June were fer- tilized but not so on the remaining occasions. The rearing experiment was performed on the second set of eggs spawned on 22 June 2004. The rearing was continued more than 200 days, but measurement and morphological observa- tion were performed only from eggs to 49 days after hatching. When spawned eggs were found in the sur- face layer of the aquarium, water samples including the eggs were transferred to a 30 l plastic tank and incubated at 25℃ with mild A airation. Hatched larvae were sucked up with a glass pipette and transferred to another 30 l plastic tank, and reared at 25℃ without any special pH control. The water was partly exchanged for fresh water and excrement removed daily. The tank was illuminated continuously over 24 h daylight periods with two fluorescent lamps in order to promote continuous feeding (Yoseda et al. 2003). Larvae, juveniles and young fish were fed several times a day with Brachionus plicatilis B from the first 18 days, Artemia larvae from days seven to 27, frozen Artemia adults from days Fig. 1. The exhibition aquarium (1.1 m3; 0.75 1.00 × × 18 to 48, and processed krill, giant tiger prawns 1.50 m) in which the parental Cyclichthys orbicularis were maintained and spawned (A); parents nestling to each and Manila clams from 48 days after hatching. other on the bottom the day before spawning (B). Spawning of porcupine puffer 209

(Sakamoto and Suzuki 1978). Melanophores Results were scattered on the body, tail and belly, with many xanthophores also on the body surface. Although the developmental stage was not The eyes were not pigmented. determined when found, the isolated epipelagic Nineteen hours after hatching, the eyes eggs were spherical, 2.2 mm in mean diameter had become pigmented and the mouth open (1.9-2.4 mm, n = 181), the embryo and primor- (3.5 mm TL, Fig. 2D). Two days after hatch- dial eyes forming within one day of spawning ing, membranous dorsal and anal fins were (Fig. 2A). separated (3.5 mm TL, Fig. 2E). Five days after Hatching occurred two days after spawn- hatching, soft rays were apparent in the pecto- ing. Hatched larvae (Fig. 2B, 2C) were 3.5 mm ral fins (3.7 mm TL, Fig. 2F), and seven days in total length (TL), with the mouth and anus later, soft rays appeared in the dorsal and anal closed. Membranous pectoral fins were obvious, fins also (3.9 mm TL, no image). and the head and trunk covered by a “vesicu- Seventeen days after hatching, 12 dorsal, 10 lar dermal sac” (Leis 1978) or “pliable shell” anal and 21 pectoral fin rays were completed,

A B

C D

E F

Fig. 2. Cyclichthys orbicularis egg of one day after spawning (2.2 mm in diameter) (A, live); hatched larvae of two days after spawning (3.5 mm TL), (B, live) and (C); 19 h after hatching (3.5 mm TL) (D); two days after hatching (3.5 mm TL) (E); five days after hatching (3.7 mm TL), (F, live). Scale bars indicate 1 mm. 210 H. Doi, T. Ishibashi and H. Sakai

A B

C D

Fig. 3. Cyclichthys orbicularis young, 17 days after hatching (7.6 mm TL) (A); 23 days (9.8 mm TL) (B); 39 days (20.8 mm TL) (C); 69 days (about 25 mm TL) (D, live).

Table 1. Growth of Cyclichthys orbicularis from hatching to 49 days Total Length (mm) After hatching Mean SD＊ Range n Just 3.5 0.1 3.2 - 3.7 48 19 hours 3.5 0.1 3.4 - 3.7 11 1 day 3.6 0.1 3.3 - 3.8 11 2 days 3.6 0.1 3.5 - 3.7 11 3 days 3.7 0.1 3.5 - 3.9 10 4 days 3.8 0.1 3.7 - 3.9 9 5 days 3.7 0.1 3.5 - 4.0 10 6 days 3.9 0.1 3.7 - 4.0 8 7 days 3.9 0.2 3.4 - 4.0 9 8 days 3.8 0.1 3.6 - 4.0 5 9 days 4.3 0.1 4.2 - 4.4 3 Fig. 4. Growth of Cyclichthys orbicularis from hatching to 17 days 7.6 - - 1 49 days. Growth rates from hatching to 8 days and thereaf- 23 days 9.8 - - 1 ter from 9 days indicated by regression equations between 39 days 16.9 5.5 13.0, 20.8 2 total length (y) and days after hatching (x). 43 days 14.6 2.3 11.9 - 20.0 10 44 days 13.4 2.0 11.1 - 16.6 7 45 days 15.6 2.4 12.7 - 19.3 7 49 days 20.0 - - 1 (9.8 mm TL, Fig. 3B), becoming unmovable 39 ＊Standard deviation. days after hatching (20.8 mm TL, Fig. 3C). After spine development sequence was represented by conditions at 52 days (about 20 mm TL, no with some rudimentary spines (lumps) appar- image) and 69 days (about 25 mm TL, Fig. 3D). ent on the dorsum (7.6 mm TL, Fig. 3A). By Growth of Cy. orbicularis from hatching to 49 twenty-three days after hatching, the rudi- days are shown in Table 1 and Fig. 4. Growth mentary spines had grown larger on the body rates from hatching to 8 days and thereafter Spawning of porcupine puffer 211 from 9 days were clearly different as visually shown in the growth lines in Fig. 4, regression Acknowledgments equations between TL (y) and days after hatch- ing (x) being y = 0.052x + 3.518 (r = 0.663, P < We thank Tomo Akita, Eriko Akashi, Yuji 0.01, n = 132) and y = 0.295x + 2.046 (r = 0.809, P Inatsugu and Takayuki Sonoyama of the < 0.01, n = 32), respectively. Shimonoseki Marine Science Museum for tech- nical help. Thanks also go to Dr. Graham Hardy Discussion for help with English.

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メイタイシガキフグの水槽内での産卵と発育

土井啓行・石橋敏章・酒井治己

フグ目ハリセンボン科メイタイシガキフグ Cyclichthys orbicularis が下関市立しものせき水族館の水 槽で産卵した。卵は分離浮遊性で平均直径は2.2 mm であり，2 日でふ化した（25℃）。ふ化仔魚の全 長は3.5 mm で，頭部および躯幹部は厚い外膜“vesicular dermal sac”で覆われていた。ふ化後17日， 全長7.6 mm で各鰭条が完成し，背面に棘原基が出現した。ふ化後39日，全長20.8 mm で棘は不動と なった。ふ化後 8 日までと 9 日以降では成長率が異なり，全長（ y ）とふ化後日数（x）の関係式は それぞれ y = 0.052 x + 3.518 および y = 0.295 x + 2.046であった。