Developmental morphology of the cyprinid fish Chela dadiburjori

Abstract

Embryonic, larval, and juvenile development of an Indian cyprinid fish, Chela dadiburjori, is described from laboratory-reared specimens. The eggs, measuring 0.7–0.9mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk and no oil globule. Hatching occurred 50–61h after fertilization at ca. 27C. The newly hatched larvae, measuring 2.4–2.6mm in body length (BL), had melanophores on the body with 14–16+14–17=29–31 myomeres. Two dark transverse bands on the ventral body surface and one melanophore on the lower margin of the eye in newly hatched larvae were diagnostic. Additionally, a cement organ for adhering to objects was present on the forehead of yolk sac larvae mm BL. The yolk was completely absorbed at 3.5mm BL. Notochord flexion was initiated at 5.0mm BL and finished at 6.0mm BL. Aggregate numbers of all fin rays were completed at 9.2mm BL. Squamation was initiated on the caudal peduncle at 8.0mm BL and completed at 10mm BL. The eggs of C. dadiburjori resembled those of the closely related species Devario malabaricus and Danio rerio. The larvae and juveniles of C. dadiburjori were also similar to those of the latter species in general morphology, especially the presence of body melanophores in newly hatched individuals and a distinctive lateral streak on the head during the period from yolk sac to postflexion larvae. However, early yolk sac larvae of C. dadiburjori were more similar to those of Devario malabaricus than Danio rerio in having a cement organ on the forehead. Larvae and juveniles of C. dadiburjori differed from those of the latter two species in pigmentation on the ventral body surface at hatching and around the mouth during the period from preflexion to early postflexion larvae and in having a dark lateral streak or band on the body in postflexion larvae and juveniles.

Full text

Developmental morphology of the cyprinid fish Chela dadiburjori
Tetsuya Sado* and Seishi Kimura
Fisheries Research Laboratory, Mie University, P.O. Box 11, Wagu, Shima, Mie 517-0703, Japan
(e-mail: TS, oz60230@cc.mie-u.ac.jp; SK, kimura-s@bio.mie-u.ac.jp)
Received: April 13, 2004 / Revised: October 18, 2004 / Accepted: October 19, 2004
Abstract Embryonic, larval, and juvenile development of an Indian cyprinid fish, Chela dadiburjori,
is described from laboratory-reared specimens. The eggs, measuring 0.7–0.9mm in diameter, were
demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk and no oil
globule. Hatching occurred 50–61h after fertilization at ca. 27°C. The newly hatched larvae, measuring
2.4–2.6mm in body length (BL), had melanophores on the body with 14–16 ⫹14–17 ⫽29–31
myomeres. Two dark transverse bands on the ventral body surface and one melanophore on the lower
margin of the eye in newly hatched larvae were diagnostic. Additionally, a cement organ for adhering
to objects was present on the forehead of yolk sac larvae ⬍3.1mm BL. The yolk was completely
absorbed at 3.5mm BL. Notochord flexion was initiated at 5.0mm BL and finished at 6.0mm BL.
Aggregate numbers of all fin rays were completed at 9.2mm BL. Squamation was initiated on the
caudal peduncle at 8.0mm BL and completed at 10mm BL. The eggs of C. dadiburjori resembled those
of the closely related species Devario malabaricus and Danio rerio. The larvae and juveniles of C.
dadiburjori were also similar to those of the latter species in general morphology, especially the
presence of body melanophores in newly hatched individuals and a distinctive lateral streak on the
head during the period from yolk sac to postflexion larvae. However, early yolk sac larvae of C.
dadiburjori were more similar to those of Devario malabaricus than Danio rerio in having a cement
organ on the forehead. Larvae and juveniles of C. dadiburjori differed from those of the latter two
species in pigmentation on the ventral body surface at hatching and around the mouth during the
period from preflexion to early postflexion larvae and in having a dark lateral streak or band on the
body in postflexion larvae and juveniles.
Key words Cyprinidae · Chela dadiburjori · Egg · Larva · Juvenile
Materials and Methods
Parental fish and egg collection.—Chela dadiburjori is dis-
tributed naturally in Tamil Nadu and Goa, India, inhabiting
lowland streams and pools (Kortmulder et al., 1990; Talwar
and Jhingran, 1991). The parental fish included 11 females
[FRLM 25915, 29164, 29166, 29506–29509, 29511, 29512,
29515, and 29517, 31–37mm in standard length (SL)] and 10
males (FRLM 26011, 29165, 29220, 29510, 29513, 29514,
29516, and 29518–29520, 29–39mm SL), bought at a pet
shop in Nagoya, Aichi, Japan. They were held at the Fisher-
ies Research Laboratory, Mie University (FRLM), in a 60-l
glass aquarium with a thin layer of gravel, an aquatic plant
(Fantinalis sp.) as a spawning substrate, and a bottom filter.
Spawning first took place on 30 July 2000, the eggs being
collected by a siphon. To measure lengths of newly hatched
larvae, the eggs spawned by the same parental fish on 2
August 2000 were collected.
Rearing method.—Eggs were transferred into a 60-l
glass aquarium containing weakly aerated water, changed at
a rate of 3–5l/day. Artificial food (Fry Feed Kyowa B; Kyowa
Hakko Kogyo, Tokyo, Japan) was provided daily to the
larvae and juveniles from 3–54 days after hatching. The
Ichthyological
Research
©The Ichthyological Society of Japan 2005
Ichthyol Res (2005) 52: 20–26
DOI 10.1007/s10228-004-0249-z
The cyprinid genus Chela, belonging to the subfamily
Danioninae (⫽Rasborinae) (sensu Howes, 1991), is
characterized by having a strongly compressed body with a
keeled ventral margin, no barbels, no symphysial knob on
the lower jaw, three teeth rows on the lower pharyngeal
bone, and elongated pectoral fins (Silas, 1958; Ba˘na˘ rescu,
1968). The genus includes six species [Chela cachius
(Hamilton), Chela caeruleostigmata (Smith), Chela
dadiburjori (Menon), Chela fasciata Silas, Chela laubuca
(Hamilton), and Chela maassi (Weber and de Beaufort)],
occurring in South and Southeast Asia (Silas, 1958;
Ba˘na˘rescu, 1968). Although members of the genus are well-
known aquarium fishes termed “hatchet barbs,” reports
on their ontogeny are unknown to date. The object of
the present study was to expand the known morphological
database of early life stages of the genus Chela. The mor-
phology of eggs, larvae, and juveniles of the Indian spe-
cies, C. dadiburjori, is described in detail from a series of
laboratory-reared specimens.

Developmental morphology of Chela dadiburjori 21
incubation and rearing temperatures ranged from 25.4° to
27.4°C.
Observations and measurements.—Observations and
measurements were made on 20 eggs, 128 larvae (FRLM
29001–29003, 29005, 29007–29012, and 29014–29036), and 20
juveniles (FRLM 29004, 29006, 29013, and 29032–29039).
All materials, except eggs, were preserved. Larvae and juve-
niles were sampled periodically from the rearing aquarium,
being preserved in 5% buffered formalin solution. Some
specimens were stained with alizarin red S to observe fin
ray formation and squamation. Identification of develop-
mental stages followed Kendall et al. (1984). Measurement
methods followed Leis and Trnski (1989), except for body
depth (BD) measured at the anus.
Results
Eggs. Demersal, almost spherical in shape, 0.7–0.9
(mean ⫾SD ⫽0.80 ⫾0.04, n⫽20) mm in diameter, with a
smooth colorless transparent chorion, a pale yellow yolk,
and no oil globule; yolk diameter ca. 74–81% of egg diam-
eter; chorion with weak adhesiveness for ca. 1min just after
fertilization (Fig. 1). Eggs laid on the lower aquatic plant
dropped to the bottom, when egg adhesiveness was lost (ca.
1min after fertilization). Embryonic development is shown
in Table 1. Hatching occurred 50–61h after fertilization at
26.5°–27.4°C.
Larvae and juveniles. General morphology.—Body
lengths (BL) of larvae and juveniles at each developmental
stage are shown in Table 2. Newly hatched larvae [2.4–2.6
(mean ⫾SD ⫽2.5 ⫾0.1, n⫽11) mm BL] characterized by
a transparent head and body, with melanophores; yolk sac
very large (38–49% BL), pear-shaped, located along venter
of head and trunk from snout tip to just before anus in yolk
sac larvae (Fig. 2A), becoming smaller with growth (Fig.
Table 1. Embryonic development of Chela dadiburjori at 26.5°–27.4°C
Time elapsed after insemination Developmental stages observed
(water temperature)
0h 24min (26.5°C) Elevation of blastodisc
1h 03min (26.7°C) 2-cell stage
1h 24min (26.8°C) 4-cell stage
2h 15min (26.6°C) 16-cell stage
3h 00min (26.7°C) 64-cell stage
3h 56min (27.0°C) Blastula stage
10h 33min (26.8°C) Closure of blastopore
11h 45min (27.1°C) Beginning of embryo formation
16h 48min (27.4°C) Formation of Kupper’s vesicle, 5–6 myomeres
18h 03min (27.4°C) Formation of optic vesicle
23h 12min (27.0°C) Formation of optic lens
30h 38min (27.2°C) Beginning of heart pulse
36h 50min (27.2°C) Melanophore deposition on eye
41h 56min (27.4°C) Melanophores appearing on dorsal body and head surface
50h 20min (27.0°C) Beginning of hatching
61h 25min (26.9°C) End of hatching
Table 2. Body length of each developmental stage
Stage Range (mm) Mean ⫾ SD n
Yolk sac larva 2.4–3.5 2.9 ⫾ 0.3 32
Preflexion larva 3.2–5.1 3.7 ⫾ 0.5 47
Flexion larva 5.0–6.0 5.6 ⫾ 0.3 9
Postflexion larva 6.0–9.1 7.4 ⫾ 0.9 40
Juvenile ⬎9.2 — 20
Fig. 1. Eggs of reared Chela dadiburjori just after fertilization. Bar
0.5mm

22 T. Sado and S. Kimura
Fig. 2. Larvae and juveniles of reared Chela dadiburjori. A Newly hatched larva, FRLM 29007, 2.4mm in body length (BL). B Yolk sac larva,
FRLM 29008, 2.9mm BL. C Preflexion larva, FRLM 29009, 4.9 mm BL. D Flexion larva, FRLM 29010, 5.7mm BL. E Postflexion larva, FRLM
29011, 6.4mm BL. F Postflexion larva, FRLM 29012, 8.8mm BL. G Juvenile, FRLM 29013, 13.4mm BL. 1, lateral view; 2, dorsal view (fin rays
omitted); 3, ventral view (fin rays omitted)

Developmental morphology of Chela dadiburjori 23
2B); yolk completely absorbed at 3.5mm BL. A cement
organ present on forehead at hatching (Fig. 2A), lost in yolk
sac larvae (3.1mm BL). Finfold of newly hatched larvae
relatively low, dorsal finfold depth less than ventral finfold
(Fig. 2A); caudal peduncle notches appearing in yolk
sac larvae (2.8mm BL). Dorsal and anal finfolds separated
from caudal fin in postflexion larvae (6.6mm BL and 6.7 mm
BL, respectively); ventral finfold lost just anterior to anus
at 12mm BL. Mouth, gill opening, and nostrils forming in
yolk sac larvae (2.8mm BL); nostrils dividing into two por-
tions in juveniles (11mm BL). Mouth of yolk sac larvae
subterminal at 2.8mm BL, changing to superior position
in yolk sac larvae at 3.5mm BL. Gas bladder visible in yolk
sac larvae (2.8mm BL), dividing into anterior and post-
erior portions at 6.3mm BL. Myomeres V-shaped in
newly hatched larvae (Fig. 2A), becoming W-shaped in
postflexion larvae (6.4mm BL). Larvae and juveniles with
14–16 ⫹14–17 ⫽29–31 myomeres (Fig. 2); notochord
flexion initiated and completed at 5.0mm BL and
6.0mm BL, respectively.
Proportions.—Head short, ca. 17–21% BL in yolk sac
larvae (ca. 3–3.5mm BL), proportion increasing with
growth, reaching to ca. 23–26% BL in juveniles ⬎9.2mm
BL. Preanal length ca. 61–64% BL initially, rapidly decreas-
ing to ca. 52–58% BL with tail extension in preflexion larval
stage (ca. 3.5–5mm BL), subsequently increasing in flexion
and postflexion larval stages, reaching to ca. 58–65% BL in
juveniles ⬎9.2 mm BL. Body depth ca. 6–8% BL initially,
increasing in flexion and postflexion larval stages, reaching
to ca. 25% BL in juvenile (14 mm BL). Pectoral fin length ca.
7–10% BL during the period from yolk sac to flexion larvae
(ca. 3–6mm BL), rapidly increasing with growth to ca. 33%
BL in juveniles (14mm BL). Eye large, ca. 44–55% of
head length (HL) in yolk sac larvae (ca. 3–3.5mm BL),
decreasing with growth to ca. 35–43% HL in juveniles
⬎9.2mm BL.
Fin development.—Dorsal fin anlage appearing at 5.8mm
BL, fin ray formation at 6.2mm BL, attaining full comple-
ment (ii, 7) at 6.6mm BL; ray segmentation initiated at
6.3mm BL, completed at 8.6 mm BL; ray branching initiated
at 11mm BL, completed at 14mm BL. Anal fin anlage
appearing at 5.6mm BL, fin ray formation at 5.9mm BL,
attaining full complement (iii, 10–12) at 7.1mm BL; ray
segmentation initiated at 6.3mm BL, completed at 9.2mm
BL; ray branching initiated at 11mm BL, completed at
14mm BL. Caudal fin anlage appearing at 4.9mm BL, fin
ray formation at 5.5mm BL, attaining full complement
(8–9 ⫹9⫽17–18) at 5.9mm BL; ray segmentation initiated
at 5.7mm BL, completed at 5.9mm BL; ray branching
initiated at 13mm BL, completed at 14mm BL. Caudal fin
rounded immediately after hatching, emarginated through-
out postflexion larval stage, but forked in juveniles (Fig. 2).
Pectoral buds present just posterior to otic capsule in newly
hatched larvae (Fig. 2A); dorsalmost fin rays forming at
7.1mm BL, attaining full complement (i, 10–12) in juveniles
(9.2mm BL); ray segmentation initiated at 7.4mm BL, com-
pleted at 13mm BL; ray branching initiated at 12mm BL,
completed at 14mm BL. Pectoral fin initially fanlike, be-
coming triangular with fin ray formation (Fig. 2A–F), elon-
gated in juveniles (10mm BL). Pelvic buds appearing at
7.0mm BL, fin ray formation at 8.0mm BL, attaining full
complement (i, 6) at 9.1mm BL; ray segmentation initiated
at 8.3mm BL, completed at 10mm BL; ray branching initi-
ated at 13mm BL, completed at 14mm BL.
Pigmentation.—Melanophore deposition on eyes already
initiated before hatching, completed in yolk sac larvae
(2.8mm BL); a single stellate melanophore on lower margin
of eye at hatching, not externally visible after completion
of melanophore deposition on eyes; ca. 10 stellate and/or
branched melanophores appearing on jaws and snout near
jaws in yolk sac and preflexion larval stages (3.0–3.5mm
BL), increasing in number, densely distributed around
mouth in preflexion larval stage (3.5–5.0mm BL), subse-
quently melanophores appearing and forming a short dark
oblique streak between snout tip and anterior margin of eye
in flexion larvae (5.0mm BL), but becoming obscure in
postflexion larvae ⬎6.4mm BL (Fig. 2E–G). Embedded,
branched and/or stellate melanophores already present just
below otic capsule at hatching and forming a short dark
lateral streak between posterior margin of eye and posterior
to otic capsule just after hatching (Fig. 2A); melanophore
streak between posterior margin of eye and anterior margin
of gas bladder present in yolk sac, preflexion, flexion, and
postflexion larval stages ⬎2.8mm BL (Fig. 2B–E), subse-
quently becoming obscure with melanophores appearing
on surface of operculum in postflexion larvae ⬎6.9mm BL
Fig. 3. Proportions of body depth (BD) A, head length (HL) B, pecto-
ral fin length (P1L) C, preanal length (PAL) D to body length (BL) and
eye diameter (ED) E to head length in reared Chela dadiburjori

24 T. Sado and S. Kimura
(Fig. 2F,G) . One to five stellate melanophores present on
dorsal contour of body at hatching (Fig. 2A), increasing in
number, along each side of dorsal midline in yolk sac larvae
(3.3mm BL), dense in flexion and postflexion larval stages
(5.0–6.3mm BL) (Fig. 2D), subsequently becoming sparse
on dorsal surface in postflexion larvae and juveniles
⬎6.3mm BL (Fig. 2E–G). Dotted melanophores appearing
on dorsolateral surface posteriorly on caudal peduncle in
postflexion larvae (8.0mm BL), subsequently increasing in
number and extending anteriorly (Fig. 2G). Dense melano-
phores forming two transverse bands on ventral body
surface in newly hatched larvae (Fig. 2A), anterior band
subsequently changing in shape and stellate melanophores
appearing between two bands in yolk sac larvae (2.9mm
BL) (Fig. 2B); melanophores densely distributed on ventral
surface of trunk in flexion larvae (5.0mm BL), disappearing
posterior to origin of ventral finfold in postflexion larval and
juvenile stages (⬎6.4mm BL) (Fig. 2E–G). Two to six stel-
late melanophores present on ventral midline of tail at
hatching (Fig. 2A), increasing in number; stellate melano-
phores appearing along each side of ventral midline of tail
in yolk sac larvae (3.1mm BL), dense during the period
from preflexion to postflexion larvae (4.7–6.0mm BL) (Fig.
2C,D), but gradually disappearing with anal fin formation
(Fig. 2E–G). Unbranched melanophores appearing on
central portion of lateral midline in yolk sac larvae (3.1mm
BL), subsequently extending anteriorly and posteriorly,
forming a midlateral line in preflexion larvae (3.5mm BL),
anterior unbranched melanophores disappearing in
postflexion larvae ⬎6.2mm BL (Fig. 2E–G); 4–6 stellate
melanophores appearing on lateral body surface near gas
bladder (4.7mm BL), subsequently extending posteriorly
and ventrally, extending to near anus in postflexion larvae
(7.6mm BL), gradually disappearing in juveniles ⬎10mm
BL (Fig. 2G); stellate melanophores appearing along lateral
midline posterior to central part of body (6.4mm BL)
(Fig. 2E), subsequently increasing in number, forming a
dark lateral streak in postflexion larvae and juveniles
⬎7.4mm BL (Fig. 2F); a dark band forming between
anteriormost trunk and caudal fin base ⬎10mm BL (Fig.
2G), three or four spots appearing on dark lateral band
anterior to central part of body in juveniles ⬎12mm BL
(Fig. 2G).
Xanthophores present on dorsal surface of head at hatch-
ing (Fig. 2A), appearing on lateral surface of head in
preflexion larvae (ca. ⬎3mm BL) (Fig. 2C). Xanthophores
present on dorsal surface of body at hatching (Fig. 2A),
gradually extending to dorsolateral surface of body and
reaching to lateral midline in postflexion larvae and juve-
niles (ca. 8–9mm BL) (Fig. 2F). Xanthophores appearing on
caudal fin base in flexion larvae (ca. ⬎5mm BL) (Fig. 2D).
Xanthophores appearing on anal fin base in postflexion
larvae (6.0mm BL) (Fig. 2E), extending laterally and poste-
riorly, reaching to lateral midline in postflexion larvae and
juveniles (ca. 8–9mm BL) (Fig. 2F). Xanthophores appear-
ing along lateral midline between operculum and caudal
peduncle in flexion larvae (ca. ⬎5mm BL) (Fig. 2D), but
becoming obscure with dark lateral streak formation during
postflexion larval and juvenile stages ⬎7.4mm BL (Fig. 2F).
Erythrophores appearing on anal and caudal fin bases in
juvenile stage (ca. ⬎9.5mm BL).
Scales.—A scale row appearing laterally on central por-
tion of caudal peduncle in postflexion larvae (8.0mm BL),
extending anteriorly along lateral midline, with dorsal and
ventral rows forming until completed around circumference
of caudal peduncle (8.3mm BL), subsequently extending
anteriorly on dorsolateral surface of body in postflexion
larval and juvenile stages ⬎9.7mm BL (Fig. 4C–E).
Squamation completed in juveniles (10mm BL).
Ecological notes.—Yolk sac larvae ⬍2.8mm BL usually
remained motionless on the bottom of the aquarium, but
sometimes moved quickly, although lacking any photopho-
bic reaction. Yolk sac larvae began to move to the surface
layer 3 or 4 days after hatching, adhering to and hanging
down from objects using a cement organ (2.8–3.0mm BL).
Yolk sac larvae ⬎3.0mm BL subsequently ascended to the
surface layer of the aquarium and took floating artificial
food. Positive phototaxis appeared at the yolk sac larval
stage ⬎2.8mm BL. Flexion larvae ⬎5.0 mm BL gradually
Fig. 4. Sequence of squamation in reared Chela dadiburjori. A
Postflexion larva, FRLM 29001, 8.0mm BL. B Postflexion larva, FRLM
29002, 8.3mm BL. C Postflexion larva, FRLM 29003, 8.5mm BL. D
Postflexion larva, FRLM 29004, 9.1mm BL. E Juvenile, FRLM 29005,
9.7mm BL. F Juvenile, FRLM 29006, 10.3mm BL. Shaded area indi-
cates squamation

Developmental morphology of Chela dadiburjori 25
descended to the midlayer, postflexion larvae and juveniles
⬎6.0mm BL occupying the mid- to lower layer. Positive
phototaxis was weak in postflexion larvae and juveniles
(⬎6.0mm BL).
Discussion
Comparison of eggs. Reports of eggs of small
Danioninae (sensu Howes, 1991) species closely related to
Chela dadiburjori (see Fang, 2003) include only Devario
malabaricus (Jerdon) (Jones, 1938) and Danio rerio
(Hamilton) (Hisaoka and Battle, 1958; Kimmel et al., 1995).
Although the eggs of C. dadiburjori resembled both of
the latter in having an almost spherical shape and colorless
chorion, and also in embryonic development, those of
C. dadiburjori have slightly smaller egg diameter [C.
dadiburjori (0.7–0.9 mm, n⫽20), Devario malabaricus
(1.1mm), and Danio rerio (0.9–1.0mm)] and narrower
perivitelline space (the ratios of yolk diameter to egg diam-
eter are 74–81% in C. dadiburjori, ca. 65% in Devario
malabaricus, and ca. 60% in Danio rerio) (Jones, 1938;
Hisaoka and Battle, 1958; Kimmel et al., 1995).
Comparisons of larvae and juveniles. Information on
early life stage morphology in species closely related to C.
dadiburjori is available for five species, Devario malabaricus
(yolk sac to probably juvenile stages ⬍62mm BL) (Jones,
1938; McClure, 1999), Devario sp. cf. aequipinnatus (yolk sac
to probably juvenile stages ⬍42mm BL) (McClure, 1999),
Danio albolineatus (Blyth) (yolk sac to probably juvenile
stages ⬍20mm BL) (McClure, 1999), Danio kerri (Smith)
(yolk sac to probably juvenile stages ⬍21mm BL)
(McClure, 1999), and Danio rerio [yolk sac to probably
juvenile stages ⬍26mm BL and squamation between 9.5
and 14.0mm TL (⫽ca. 8–11mm BL)] (Hisaoka and Battle,
1958; Waterman, 1970; Armstrong, 1973; Kimmel et al., 1995;
McClure, 1999). Although the larval and juvenile
descriptions of the latter five species by McClure (1999)
cannot be compared in detail owing to his rough description
of the pigmentation patterns on only body surface based on
the specimens preserved in 70% ethanol, the morphology of
larvae and juveniles of C. dadiburjori resembled the latter
five species in general appearance, including fin ray
formation, squamation, pigmentation (presence of melano-
phores in newly hatched larvae), and time to notochord
flexion (after onset of larval swimming) (Jones, 1938;
Hisaoka and Battle, 1958; Waterman, 1970; Armstrong, 1973;
Kimmel et al., 1995; McClure, 1999). Chela dadiburjori
resembled both Devario malabaricus and Danio rerio in
having a dark lateral streak on the head during from yolk
sac to postflexion larval stages (Jones, 1938; Hisaoka and
Battle, 1958; Kimmel et al., 1995), and Devario sp. (cf. D.
aequipinnatus) in having melanophores on dorsal and
ventral midlines near tail tip and just anterior to anus in
newly hatched larvae (McClure, 1999). In particular, newly
hatched larvae of C. dadiburjori are more similar to those of
Devario malabaricus because both species have a cement
organ on the forehead until the larvae begin swimming
(Jones, 1938). This feature indicates a close relationship
between the genera Chela and Devario (Fang, 2003). Chela
dadiburjori has, however, unique pigmentation features
during the larval and juvenile stages: a single melanophore
on the lower margin of the eye (⬍2.8mm BL), a dark lateral
streak or band on body in the postflexion larval and juvenile
stages (⬎7.4mm BL), and three or four dark lateral spots on
body in the juvenile stage (⬎12mm BL) (absent in Devario
malabaricus, Devario sp. (cf. D. aequipinnatus), Danio
albolineatus, Danio kerri, and Danio rerio), two melano-
phore bands on the ventral surface of the trunk (⬍2.8mm
BL) (melanophores sparsely distributed in the latter five
species), and dense pigmentation around the mouth during
the period from preflexion to postflexion larval stages (3.5–
6.4mm BL) (melanophores sparsely present in Devario
malabaricus and no data in the rest species) (Jones, 1938;
Hisaoka and Battle, 1958; Kimmel et al., 1995; McClure,
1999).
Ecological considerations. Chela dadiburjori laid small
eggs on the aquatic plant provided in this study. Newly
hatched larvae were also small, with body melanophores
and a cement organ on the forehead, and showed no pho-
tophobic reaction. These morphological and ecological
characteristics of C. dadiburjori agree well with as guild
“A. Nonguarders—A.1. Open substratum spawners—A.1.5.
Phytophilis,” as defined by Balon (1975) in his classification
of fishes into 32 guilds based on the reproductive ecology
and ethology. The former guild is characterized by well-
developed embryonic respiration organs, which enable the
fish to survive in poorly oxygenated waters (Balon, 1975).
Chela dadiburjori inhabits lowland streams and pools in
India, being potentially exposed to low-oxygen waters in its
natural environment.
Acknowledgments We express our sincere gratitude to M. Kashiwagi
(Mie University) for his advice and suggestions during this study.
We greatly appreciate the assistance of the students of FRLM in the
rearing experiment. G.S. Hardy (Whangarei, New Zealand) provided
critical comments on the manuscript and great help with the English.
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