Development of eggs,larvae and juveniles of the labrid fish,Halichoeres poecilopterus,reared in the laboratory

Embryonic, larval and juvenile development of the labrid fish,Halichoeres poecilopterus, is described using a laboratory-reared series. The eggs, measuring 0.60–0.72 mm in diameter, were pelagic and spherical with a single oil globule (0.12–0.16 mm in diameter). Hatching occurred 18 h 48 min after spawning. The newly-hatched larvae, measuring 1.46–1.70 mm TL, had 8–114 + 16–18 myomeres. A conspicuous melanophore appeared on the dorsal finfold 8 h after hatching, at ca. 2 mm TL. The yolk was completely absorbed 3 days after hatching, at 2.52–2.72 mm TL. Flexion of the notochord started at ca. 6 mm TL and was finished at ca. 8 mm TL. Aggregate numbers of all fin rays were completed at ca. 14 mm TL. Squamation was almost completed at ca. 20 mm TL.     

Embryonic, larval and juvenile development of the roughskin sculpin,Trachidermus fasciatus (Scorpaeniformes: Cottidae)

Embryonic, larval and juvenile development of the catadromous roughskin sculpin,Trachidermus fasciatus, were described using eggs spawned in an aquarium. The eggs, measuring 1.98–2.21 mm in diameter, were light reddish-yellow and had many oil globules, 0.05–0.18 mm in diameter. Hatching occurred 30 days after spawning at 2.3–11.3°C. The newly-hatched larvae, measuring 6.9–7.3 mm BL, had a single oil globule, 9–10+25–26=34–36 myomeres and 6 or 7 large stellate melanophores dorsally along the gut. The yolk was almost resorbed, number of pectoral-fin rays attained 16–17, and two parietal, one nuchal and four preopercular spines were formed, 5 days after hatching, at 8.2–8.4 mm BL. The oil globule disappeared, and one supracleithral spine was formed, 11 days after hatching, at 8.9–9.5 mm BL. Notochord flexion began 15 days after hatching, at 9.7–10.3 mm BL. A posttemporal spine was formed 20 days after hatching, at 10.7–10.9 mm BL. The first dorsal fin spines (VII–VIII), second dorsal fin and anal fin rays (18–19, 16–18, respectively) appeared 23 days after hatching, at 12.0–13.7 mm BL. The pelvic fin spine and rays (I, 4) were formed and black bands on the head and sides of the body began to develop 27 days after hatching, at 13.8–15.8 mm BL. Newly-hatched larvae swam just below the surface in the aquaria. Preflexion larvae (8.9–9.5 mm BL), in which the oil globule had disappeared, swam in the middle layer, while juveniles (13.8–15.8 mm BL) began swimming on the bottom of the aquaria. Swimming behavior observed in the aquaria suggested that the fish started to change to a demersal existence at the juvenile stage.     

Pelagic eggs and larvae of Coelorinchus kishinouyei (Gadiformes: Macrouridae) collected from Suruga Bay, Japan

Pelagic eggs and larvae of the macrourid fish Coelorinchus kishinouyei, collected from Suruga Bay, southern Japan and subsequently identified by 16S rRNA gene nucleotide sequences, are described. The spherical eggs, 1.18–1.31 mm in diameter, contained a single oil globule, 0.28–0.33 mm in diameter, and had hexagonally patterned ornamentation on the chorion, 0.017–0.022 mm in width. Melanophores were present on the embryo, yolk and oil globule after the blastopore had closed. Within 1 day after hatching, the body axis of the yolk-sac larvae was bent slightly at the anterior trunk region. During this stage many melanophores formed on the head, trunk, tail, yolk and oil globule, along with small irregular wrinkles on the dorsal and ventral finfolds. Pelagic eggs (after the caudal end of the embryo had detached from the yolk) and yolk-sac larvae also developed xanthophores on the embryo and yolk, and head, trunk, dorsal and ventral finfolds just before tail tip, and yolk, respectively. The pelagic larvae had a short tail, stalked pectoral-fin base and no elongate first dorsal and pelvic-fin rays. Three clusters of melanophores were present on the tail (anterior two embedded to muscle and one just before tail tip subsequently lost with development) and a cluster around the anus (beyond 3.9 mm head length). Nucleotide sequence analyses of comparative adult specimens appeared to confirm a previous proposal that C. productus is a junior synonym of C. anatirostris.     

Embryonic and larval development of a Japanese spinous loach,Cobitis takatsuensis

The embryonic and larval development ofCobitis takatsuensis, a mountain stream spinous loach, was surveyed by incubating artificially inseminated eggs. The mean diameter of the inflated eggs and mean total length of newly-hatched larvae were 2.7 mm and 5.7 mm, respectively. The eggs were spherical, transparent and unpigmented, with a pale yellow yolk and no oil globule. The daily cumulative temperature to hatching was estimated to be 70–110°C. day. Hatched larvae were unpigmented with outer gill filaments on their cheeks, as in otherCobitis species, but the melanophores were comparatively less obvious at each developmental stage. The larvae started feeding eleven days after hatching yolk absorption being completed sixteen days after hatching. All the fin rays were fully developed and the juvenile stage reached at 16 mm TL, 38 days after hatching. Embryonic and larval developmental traits ofC. takatsuensis, such as egg size, clutch size and larval pigmentation, were similar to the Korean species,Niwaella multifasciata, that lives in the upper reaches of the Nak-tong river, andN. delicata, which inhabits Japanese mountain streams, rather than to its congeners. Among cobitine fishes, the spawning of a small number of larger eggs yielding larger larvae without pigmentation, characteristics shared byC. takatsuensis, N. multifasciata andN. delicata, is attributable to adaptation to cold mountain streams.     

Development of eggs, larvae and juveniles of laboratory-reared blue whiting,Sillago parvisquamis (Percoidei: Sillaginidae)

The embryonic, larval and juvenile development of blue whiting,Sillago parvisquamis Gill, are described from a series of laboratory-reared specimens. Mean egg diameter and mean total length (TL) of newly-hatched larvae were 0.71 mm and 1.58 mm, respectively. The eggs were non-adhesive, buoyant and spherical with an oil globule (mean diameter 0.18 mm). Hatching occurred about 20 hours after fertilization at a temperature of 24.0–25.0°C, newly-hatched larvae having 38–40 myomeres. The yolk and oil globule were completely absorbed 3 days after hatching at 2.8–3.2 (mean 3.0) mm TL. Notochord flexion was completed by 7.2–8.2 (7.7) mm TL, and pectoral and caudal fin rays fully developed by approximately 10 mm and 8.5 mm TL, respectively. Completion of fin development occurred in the following sequence: caudal, pectoral, anal and second dorsal, first dorsal and pelvic, the last-mentioned by approximately 11 mm TL. The larvae ofS. parvisquamis andS. japonica, which closely resemble each other in general morphology and pigmentation, could be distinguished as follows. Newly-hatchedS. parvisquamis larvae had more myomeres thanS. japonica (38–40 vs. 32–34) and more melanophores on the dorsal surface of the body (19–28 vs. about 40).Sillago japonica had a vertical band of melanophores on the caudal peduncle, which was lacking in postflexionS. parvisquamis larvae. In addition, juveniles ofS. parvisquamis (larger than 23 mm TL) had melanophores on the body extending anteriorly to below the lateral line to form a midlateral band, whereas no obvious band occurred on similarly-sizedS. japonica juveniles.     

Larval development of the back keeled mullet Liza carinata

The sex ratio of the fish used in this study, was 1:1.5 females to males. Natural spawning of the keelback mullet, Liza carinata, in captivity was possible and occurred between December and February. The mean fertilized egg diameter of L. carinata was 0.8±.051 mm. Hatching took place after 36 h at 23°C. The mean total length of the just-hatched larvae was 2.0±0.179 mm. Larval developmental stages, growth, and morphological changes of L. carinata were described on the basis of a series of specimens (391 in total) reared from days 1 to 89 after hatching. Details of the larval developmental stages were drawn and photographed, with special reference being taken of morphological transformations. Larvae completed yolk absorption on the sixth day after hatching, and opened their mouths on day 4. Notochord flexion started on the sixteenth day at 5.0 mm total length. Transformation from larval to juvenile stage occurred between days 30 and 51 after hatching. The maximum size of larvae and the minimum size of juveniles which appeared during the transitional period were 19 and 9.9 mm TL, respectively. By day 51, all the larvae had changed into juveniles with a mean TL of 29.3±6.429 mm. The juveniles started to change into young adults with three anal spines by day 88 at a TL of 62 mm. This revised version was published online in September 2006 with corrections to the Cover Date.     

Induction of ovarian maturation and development of eggs,larvae and juveniles of the tonguefish,Cynoglossus abbreviates,reared in the laboratory

Cynoglossus abbreviatus spawns from mid-March to mid-April in the Sea of Shimabara in Kyushu. During the spawning season ovarian maturation was successfully induced by injection of the pituitary homogenate ofHypophthalmichthys molitrix. The dose of the aceton-dried pituitary homogenate was 6.5 mg/kg body weight ofC. abbreviatus. It took about 2 days for ovulation after injection at a water temperature of 14 to 16°C. Artificial fertilizations were accomplished on March 29, 1974 and again on April 7, 1984, using the females matured by hormone injection in the latter case only. The larvae were reared on the rotifers,Artemia nauplii,Tigriopus japonicus and copepods collected from the sea over a period of 113 days in 1974 and 58 days in 1984. The eggs were pelagic, spherical, 1.19–1.23 mm in diameter and had 30–50 oilglobules of 0.068–0.095 mm in diameter, and the perivitelline space was narrow. The incubation period was 90–98 hours at a water temperature of 14 to 16°C. The newly hatched larvae were 3.18–3.45 mm TL and had 61–64 myomeres. The larvae had many melanophores and xanthophores on the body, forming three bands on the caudal region, but were lacking chromatophores on the finfolds. The yolk was completely absorbed when the larvae attained a size of 4.7–5.6 mm TL 8 days after hatching. A single elongated dosai fin ray developed on the head in the 8-day old larvae. The ray was reduced in size as long as the other rays 1 or 2 days after metamorphosis. The rudiment of pectoral fins were found on the both sides of the body in the 2-day old larvae, but two of them disappeared after metamorphosis. A pelvic fin first appeared as a ventral bud just anterior to the gut in the larva of 8.39 mm TL. The full count of 4 rays was observed on the larva of 10.83 mm TL. Metamorphosis began 22 days after hatching when the larvae were 11.20 mm TL. The right eye began to shift the left side of the head at night and reached to the final place after 8.5 hours. It took about 36 hours to complete the metamorphosis, including the eye movement and fusion of the hole in the rostral beak. At the last stage of metamorphosis, the dosal, caudal, anal and ventral fins became confluent. The larvae reached the juvenile stage at a size of 13.5–14.0 mm TL, approximately 28 days after hatchling. The growth of larvae reared in 1974 is expressed by the following equations: Y₁ = 3.448 · 1.0507^x (8≦X≦28) Y₂ = 6.3322 · 1.0275^x (28≦X≦75) where Y is the total length (mm) and X is the number of days after hatching. Growth rate changed after metamorphosis.     

Embryonic and early larval development of <Emphasis Type="Italic">Cottus czerskii</Emphasis> Berg, 1913 (Scorpaeniformes: Cottidae)

The embryonic and early larval development of the Cherskii’s sculpin Cottus czerskii Berg, 1913 was studied. The duration of the embryonic period was 21 days at a water temperature of 9–10°C. Pelagic larvae of approximately 8.0 mm total length leave the egg envelopes, with a large rounded yolk sac with one large oil globule, 10–12 trunk and 30–31 precaudal myomeres and several large melanophores on the yolk sac, 2 melanophores in the peritoneal region, and 30 melanophores in a postanal ventral row. At 11 days after hatching at a length of 9.0 mm, the yolk sac is completely resorbed and the number of myomeres remains the same; seven rays become visible in the caudal fin. The fully formed larva of C. czerskii has an elongated body, a small head, a rounded snout, and an oblong tail part. The melanophores are located in the peritoneal area above the gut, in the abdominal area, and in the postanal ventral row. Armament in the form of spines on the top of the head is absent, pointing to the affiliation of the species that we studied to the Cottus–Leptocottus phenetic group.     

Development of eggs,larvae and juveniles of the puffer,Takifugu chrysops,reared in the laboratory

The artificial fertilization of the puffer,Takifugu chrysops (Hilgendorf), was carried out at Sajima in Yokosuka City on May 22, 1984. Hatched larvae were reared for a period of about 150 days. The spawning period seems to extend from mid to late May in the eastern part of Sagami Bay. The eggs were spherical, pale milky white and semitransparent, demersal and adhesive in nature, measuring 1.32±0.04 mm in diamter, and with a cluster of small oil-globules. The incubation period was about 162 hours at a water temperature of 17.4 to 21.8°C. During embryonic development, the only pigment cells that appeared on the embryo were the black chromatophores. The newly hatched larvae measured from 2.72 to 3.06 mm TL, averaging 2.87±0.1 mm TL, and 22–23 (9 + 13?14) myomeres. At yolk absorption, 4 days after hatching, the larvae attained 3.64–3.79 mm TL. On the 11th day, postlarvae averaged 4.69±0.24 mm TL. Larval finfolds disappeared and rudimental dorsal, anal and caudal fins were formed. There were two large clusters of melanophores, one on the back, exteding from the mid-base of the dorsal fin to the caudal peduncle region, the other along the anal fin base. The color of the body began to turn pale green to brownish-orange and spinelike scales appeared on the belly. Eighteen days after hatching (7.02±0.27 mm TL), the caudal notochord began to turn up and a “constriction” appeared on the posterior margin of the caudal fin membrane. This notch moved upwards as the notochord upturning advances. The larvae attained full fin ray counts and reached the juvenile stage at 9.1-9.5 mm TL, 24 days after hatching. Characteristic black blotches on the back and specific brownish orange body color appeared at the stage of 20 mm TL, 24 days after hatching. The growth during the larval stage and early juvenile stage (24 to 51 days after hatching) were expressed by the following equations, wherey is total length (mm) andx is days after hatching.y ₁=2.8424× 1.0509⁹ (0≦x≦24)y ₂ = 3.7872×1.0372^x (24≦x≦51)     

美洲鲥胚胎及仔稚鱼的发育

对美洲鲥(Alosa sapidissima)早期生活史阶段的生长发育特征进行了观察和测量, 描述了胚胎和仔、稚鱼的生长发育特征。美洲鲥受精卵球形、无油球, 为沉性卵, 卵径2.85-3.28 mm。在水温20.3℃-21.9℃孵化条件下, 经过82h 孵化出膜, 根据其胚胎发育过程的形态特征, 胚胎发育分为受精卵、卵裂期、囊胚期、原肠胚期、神经胚期、器官形成期和出膜期7 个发育阶段。美洲鲥初孵仔鱼全长为(8.56±0.36) mm, 其卵黄囊体积为(4.57±0.77) mm3。1 日龄仔鱼脑部发育明显, 口张开, 肛门开通, 胸鳍形成。2 日龄仔鱼卵黄囊体积(0.71±0.23)mm3, 只有刚孵化的15.54%。3 日龄仔鱼经过1d 的混合营养期, 卵黄被完全吸收, 4 日龄仔鱼完全营外源性营养, 卵黄囊的体积(V)随孵化时间(h)的变化方程为V=4.1583e?0.0356h(R2=0.9901)。此后, 背鳍鳍条、尾鳍鳍条、臀鳍鳍条和腹鳍鳍条相继在晚期仔鱼出现, 9 日龄仔鱼尾椎开始弯曲, 21 日龄仔鱼尾椎弯曲完成。27 日龄鱼鳞开始形成, 到33 日龄稚鱼全身披鳞, 个体发育进入幼鱼期, 仔稚鱼期间的生长模型方程为: TL=0.0049D2+0.5091D+9.2578 (R2=0.9885, TL 为全长, D 为日龄)。       

Early development of the endangered freshwater goby, Rhinogobius sp. BI (Gobiidae)

The early development of the endangered freshwater goby, Rhinogobius sp. BI (ogasawara-yoshinobori in Japanese), was described in the course of a serial rearing experiment over generations as ex situ preservation. The eggs, measuring 2.0 mm in long diameter and 0.7 mm in short diameter, were elliptical with a colorless transparent chorion, a slightly yellowish yolk, and some oil globules. Hatching occurred naturally at 6 to 7 days after spawning at 24.0°C. Newly hatched larvae, measuring 3.2–3.4 mm in total length (TL), had opened mouth and a globular yolk sac. The yolk was completely absorbed at 3.5 mm TL (5 days after hatching). Notochord flexion initiated at 5.7 mm TL (18 days) and finished at <9.1 mm TL (30 days). First dorsal fin began to form in postflexion larvae at 10.0 mm TL (40 days), and a full complement was attained at 11.6 mm TL (45 days). Second dorsal fin emerged at 5.7 mm TL (18 days); full count was attained and segmentation initiated at 9.1 mm TL (30 days). Anal fin anlage appeared at 5.7 mm TL (18 days); its ray count was completed and segmentation initiated at 9.1 mm TL (30 days), and branching at 15.6 mm TL (60 days). Caudal fin support appeared at 4.5 mm TL (15 days); segmentation initiated at 6.0 mm TL (24 days) and branching at 10.0 mm TL (40 days). Fanlike pectoral fin present in newly hatched larvae. Pectoral fin rays appeared at 10.0 mm TL (40 days), and its ray count completed at 15.6 mm TL (60 days). Pelvic fin projected at 9.1 mm TL (30 days), and a sucking disc partially formed at 11.6 mm TL (45 days). Aggregate numbers of all fin rays were completed at 15.6 mm TL in 60 days after hatching. Pelagic period continued for about 40 days, and settlement was completed in postflexion larvae at 45 days.     

贝氏高原鳅胚胎和仔鱼的形态发育

通过人工授精获得受精卵,对贝氏高原鳅胚胎和仔鱼的发育过程进行了观察和描述。结果表明,成熟卵淡黄色,卵径较小(直径0.94－1.10mm),遇水后产生强黏性。在水温9.0－12.8℃下,胚盘在受精后4h20min开始分裂,在19h50min和27h40min时达到囊胚期和原肠期,64h40min胚孔封闭,287h时部分胚胎开始出膜,405h30min全部出膜。初孵仔鱼全长(4.32±0.23)mm,肌节36－38对,眼和躯干部黑色素细胞明显,胸鳍原基发育良好。出膜后第5天仔鱼体侧和头部出现浓密的感觉芽。到第8天时全长(6.05±0.41)mm,卵黄吸收完全。仔鱼鳔一室和鳔二室分别于出膜后第30天和第50天形成。第55天的仔鱼全长(14.05±1.01)mm,肌节52－53对,体侧出现7－8条黑色素带,各鳍鳍条数目与成鱼基本一致,但仍有少量鳍褶存在。仔鱼的卵黄囊体积减小速度为0.027mm3/d,鱼体长度生长、鱼体长度性状间的比例关系并不相同,其中,肛后长／全长比例随胚后发育逐渐增加,由初出膜时的31%增加到最后的42％左右。     

Development of the cottid fish,Pseudoblennius percoides,reared in the laboratory,with brief descriptions of juvenileP. marmoratus andP. zonostigma

Embryonic, larval and juvenile development of the cottid fish,Pseudoblennius percoides were described on the basis of a series of laboratory-reared specimens. The eggs were demersal, adhesive, almost spherical in shape, measuring 1.66–1.82 mm in diameter, and with numerous various-sized oil globules. Neighboring eggs adhered to each other to form an egg mass. Hatching occurred between 13 and 16 days after spawning at a water temperature of 15.4 to I6.5°C. Newly hatched larvae measured from 6.5 to 7.3 mm, averaging 6.9 mm TL, and possessed 40 myomeres. Absorption of the yolk was completed at about 7.5 mm TL. Flexion of the notochord started and finished at about l0 mm TL and about 14 mm TL, respectively. Aggregate numbers of all fin rays were completed at over 16 mm TL, when the larvae reached the juvenile stage. The pigment pattern became the same as that of adults in juveniles longer than 25 mm TL. Lateral lines were completed at over 44 mm TL, when the juveniles attained to the young stage. The early stages of this species were clearly distinguished from those ofP. cottoides, and the juveniles of fourPseudoblennius species, i.e.P. percoides, P. cottoides, P. marmoratus andP. zonostigma, could be identified mainly by their pigment patterns.     

Pelagic eggs and larvae of Coryphaenoides marginatus (Gadiformes: Macrouridae) collected from Suruga Bay, Japan

The pelagic eggs, yolk-sac and pelagic larvae of the macrourid fish, Coryphaenoides marginatus, from Suruga Bay in southern Japan, are described. The identification of the pelagic eggs based on 16S rRNA gene nucleotide sequences agreed with that obtained from morphological analyses. The spherical eggs, 1.14–1.30 mm in diameter, contained a single oil globule 0.30–0.38 mm in diameter, and had hexagonally patterned ornamentation on the chorion, 0.025–0.033 mm in width. Many melanophores were present on the anterodorsal region of the embryo after the caudal end had detached from the yolk. Within a day after hatching, each of the yolk-sac larvae had a body axis that was bent slightly at the anterior trunk region, many dorsal and lateral melanophores on the trunk plus several on the gut, and small irregular wrinkles on the dorsal and anal fin membranes. The pelagic larvae had a short caudal region in comparison to other known congeners (length 2.0–3.2+ times head length vs. 4–7, respectively), a short stalked pectoral fin base, and no elongate first dorsal and pelvic fin rays. They were further characterized by the presence of numerous very dense melanophores from just behind the eye to the anterior part of the caudal region at 5.1 mm head length (25.8+ mm total length). The significant difference in vertical distribution between the pelagic eggs and larvae (dominant depths ca. 200–350 m vs. ca. 10–100 m, respectively), with no subsequent collection of pelagic larvae with greater than 6 mm head length, indicate two stages (rising and falling) of ontogenic vertical migration.     

Induction of ovarian maturation and development of eggs,Larvae and Juveniles of the Puffer,Takifugu exascurus,Reared in the Laboratory

Ovarian maturation of the pufferTakifugu exascurus (Jordan et Snyder) was induced, and embryonic, larval and juvenile development was observed. The brood fish were collected in Tassha Bay, Sado Island (38°05′N, 138°15′E), during the spawning season in 1986 which seemed to extend from late June to mid-July. To each female 3 mg acetone-dried pituitary ofHypophthalmichthys molitrix was injected to induce ovarian maturation, which took place in about 77 hours at a water temperature of 19.5–21.0°C. The eggs obtained by hormone injection were artificially fertilized with the milt from a collected male. The hatched larvae were fed successively on rotifersBrachionus plicatilis, Artemia nauplii and minced fish meat, and reared for a period of about one year. The eggs were spherical, 1.24±0.04mm in diameter, demersal and adhesive. The egg-membrane Was transparent and yolk was orange in color, containing a cluster of small oil-globules. The incubation period was about 160 hours at a water temperature of 18.5–21.0°C. The newly-hatched larvae, measuring 2.9– 3.1 mm TL, had 8+15 = 23 myomeres. Absorption of the yolk was completed 3 days after hatching, by which time the larvae had attained 3.5–3.6 mm TL. Larval finfolds disappeared and rudimentary dorsal, anal and caudal fins formed at 4.1–4.4 mm TL, in 6 days after hatching. In 9-day old larva (5.4 mm TL), fin ray rudiments appeared on the dosai, anal and caudal fins and spine-like scale formed on the belly. In 16-day old specimens, 9.1–10.2 mm TL, the full complements of fin rays were completed on all the fins and the fish reached the juvenile stage. The growth of larvae and juveniles reared in 1986–1987 is expressed by the following equations, where y is total length (mm) and x is days after hatching. y₁ = 2.9420· 1.0639^x 0 ≦ x ≦ 19 (r = 0.998) y₂ = 4.0286· 1.0464^x 19≦ x ≦ 33 (r = 0.998) y₃ = 9.8854· 1.0180^x 33 ≦ x ≦ 72 (r = 0.996) y₄ = 20.1555· 1.0080^x 72 ≦ x ≦ 115 (r = 0.998) y₅ = 28.0610· 1.0049^x 115 ≦ x ≦ 202 (r = 0.995)     

Development of the eggs and larvae of the pike eel,Muraenesox cinereus

Embryonic and larval development of the pike eel,Muraenesox cinereus, are described following natural fertilization in the laboratory. Eggs are pelagic and spherical with diameters from 1.8 to 2.1 mm and have a colorless, transparent chorion and numerous oil globules. Hatching occurs 36 hours after spawning at a water temperature of 25°C. Newly-hatched larvae are 5.8 mm in mean TL, and the number of myomeres averages 86. Absorption of the yolk is completed 8 days after hatching, at 9–10 mm TL. Larvae survive for 10 days without food supply. At this time they are 11.2 mm in mean TL and have 97 + 55=152 myomeres, which is a diagnostic character of this species. They have large eyes and well-developed jaws with sharp teeth.     

Growth and morphological development of laboratory-reared larval and juvenile <Emphasis Type="Italic">Hemibagrus filamentus</Emphasis> (Siluriformes: Bagridae)

Morphological development in laboratory-reared larval and juvenile Hemibagrus filamentus, and behavioral features observed under rearing conditions are described. Body lengths (BL) of larvae and juveniles were 3.8 ± 0.2 (mean ± SD) mm just after hatching and 11.7 ± 1.6 mm on day 15, reaching 26.5 ± 5.4 mm on day 30 after hatching. Aggregate fin ray numbers (for caudal fin, except for procurrent rays) attained full complements in specimens larger than 12.9 mm BL. A maxillary barbel bud appeared on day 0, and all larvae initiated feeding on day 3 with the development of mandibular barbels and conical teeth. Pectoral fin buds and primordial nostrils were present on day 1. Notochord flexion began on day 3, and the yolk was completely absorbed by day 4. Melanophores were scarce at hatching, but increased with growth to cover almost the entire body except the ventral surface of the head and body. Body proportions became relatively constant in juveniles, excepting maxillary barbel length that continued to increase, reaching over 40% BL. Fish were negatively phototactic from day 1. Cannibalism was observed from day 6, continuing to the juvenile stage.     

Characterization of the initial ontogeny of Leiarius marmoratus (GILL, 1870): larvae to juvenile

Aiming to provide data on the biology of Leiarius marmoratus, which will aid in its production in captivity, as well as in studies for its preservation in the environment, this work had as objectives: analyze and describe main morphological alterations during larval ontogeny of the species. We analyzed 205 individuals, obtained by induced reproduction (Colpani Pisciculture) and kept in CEPTA/ICMBIO, Pirassununga, São Paulo, Brazil. Analyses were performed from hatching moment to 30th day. The specimens were classified into two periods: larval (Stages: vitelline, pre‐flexion, flexion, post‐flexion) and juvenile. Hatched larvae showed ident chromatophores only at anterior and posterior extremities of yolk sac. The standard length ranged from 2.16 mm (yolk) to 28.84 mm (Youth). Dorsal fin rays were initially observed at flexion stage (12–14 rays). Major alterations occurred during post‐flexion/juvenile stage, when dorsal, pectoral, pelvic, anal, and caudal fins were observed and pigmentation intensified throughout the lateral region, forming bands in the body, one between the end of the head and beginning of dorsal to pelvic fin, and another one beginning at dorsal to caudal peduncle and four longitudinal at the head.     

Comparison of laboratory-reared eggs, embryos and larvae of five labrid fishes

Eggs, embryos and larvae of five labrid fishes, Thalassoma cupido, Pteragogus flagellifer, Pseudolabrus japonicus, Halichoeres tenuispinnis, and H. poecilopterus, reared in the laboratory are described and compared. The eggs were buoyant and spherical, with a single, spherical oil globule. P. japonicus eggs were unique in lacking melanophores on the oil globule. Eggs of the remaining species closely resembled each other, except in diameter. Incubation periods were short, ranging from ca. 19 h in H. poecilopterus to ca. 31 h in P. japonicus. The newly-hatched embryos also resembled each other, having a short tail and large oval or pear-shaped yolksac, the anterior tip of which extended beyond the snout. The single oil globule was located at the anterior tip of the yolk. As the yolksac diminished with growth, its anterior tip moved posteriorly. The yolk and oil globule were completely absorbed 3 or 4 days after hatching. In all free embryos and larvae except for Pteragogus flagellifer, needle-like projections appeared on both the dorsal and anal finfold margins 12 h to 1 day after hatching. Although morphology of free embryos and larvae of all five species was very similar, differences in pigmentation, location of the anus, and the needle-like projections were apparent. Artificial keys to the newly-hatched embryos and larvae are given.     

Growth and morphological development of laboratory-reared larval and juvenile bighead catfish Clarias macrocephalus (Siluriformes: Clariidae)

Morphological development in laboratory-reared larval and juvenile bighead catfish Clarias macrocephalus is described. Body length (BL) of larvae and juveniles was 3.4 ± 0.3 (mean ± SD) mm just after hatching, reaching 11.3 ± 1.0 mm by day 16, and 24.2 ± 2.8 mm by day 40. Overall aggregate fin ray numbers (except for caudal fin procurrent rays) attained full complements by 15.2 mm BL. Gill buds appeared on day 0, those of barbels (four pairs) and primordial nostrils on day 1, and pectoral fins on day 3. All larvae began feeding by day 3. Conical teeth were observed on day 7. Notochord flexion began on day 2, the yolk being completely absorbed during days 7–9. Melanophores were scarce at hatching, increasing with growth to cover almost the entire body except the ventral surface of the abdominal cavity. Proportions of head length, pre-anal length, body depth, eye diameter, and maxillary barbel length became relatively constant after yolk absorption, those of snout length and upper jaw length increasing until ca. 12–13 mm BL and decreasing thereafter. Suprabranchial organ started developing in postflexion larval stage larger than ca. 11.0 mm BL (day 16), and air-breathing was suggested to be functional at that time.