Growth and morphological development of laboratory-reared larval and juvenile three-spot gourami <Emphasis Type="Italic">Trichogaster trichopterus</Emphasis>

Morphological development, including the body proportions, fins, pigmentation and labyrinth organ, in laboratory-hatched larval and juvenile three-spot gourami Trichogaster trichopterus was described. In addition, some wild larval and juvenile specimens were observed for comparison. Body lengths of larvae and juveniles were 2.5 ± 0.1 mm just after hatching (day 0) and 9.2 ± 1.4 mm on day 22, reaching 20.4 ± 5.0 mm on day 40. Aggregate fin ray numbers attained their full complements in juveniles >11.9 mm BL. Preflexion larvae started feeding on day 3 following upper and lower jaw formation, the yolk being completely absorbed by day 11. Subsequently, oblong conical teeth appeared in postflexion larvae >6.4 mm BL (day 13). Melanophores on the body increased with growth, and a large spot started forming at the caudal margin of the body in flexion postlarvae >6.7 mm BL, followed by a second large spot positioned posteriorly on the midline in postflexion larvae >8.6 mm BL. The labyrinth organ differentiated in postflexion larvae >7.9 mm BL (day 19). For eye diameter and the first soft fin ray of pelvic fin length, the proportions in laboratory-reared specimens were smaller than those in wild specimens in 18.5–24.5 mm BL. The pigmentation pattern of laboratory-reared fish did not distinctively differ from that in the wild ones. Comparisons with larval and juvenile morphology of a congener T. pectoralis revealed several distinct differences, particularly in the numbers of myomeres, pigmentations and the proportional length of the first soft fin ray of the pelvic fin.     

Growth and morphological development of laboratory-reared larval and juvenile Pangasianodon hypophthalmus

The morphological development, including the fins, body proportions and pigmentation, of laboratory-reared larval and juvenile Pangasianodon hypophthalmus was described and their behavioral features were observed under rearing conditions. Body lengths (BL) of larvae and juveniles were 3.0 ± 0.2 (mean ± SD) mm just after hatching, and 12.9 ± 1.1 mm on day 13, reaching 23.4 ± 1.8 mm on day 25 after hatching. Aggregate fin ray numbers (for caudal fin, principal soft ray number) attained their full complements in specimens larger than 12.8 mm BL. Notochord flexion began in yolksac larvae on day 0 (10.5 h after hatching), with teeth buds and barbels appearing with jaw formation in yolksac flexion larvae on day 1. Melanophores on the body increased with growth, with a broad vertical band forming on the lateral line and an oblique band extending from above the pectoral fin base towards the forepart of the anal fin during the postflexion larval and juvenile stages. Body proportions became relatively constant in juveniles, except for maxillary barbel length (MBL), which continued to decrease. Yolksac flexion larvae started feeding on day 2 with the onset of intense cannibalism. Yolks were completely absorbed by day 3, and cannibalism ended by day 6. Subsequently, fish displayed a schooling behavior with growth, preferring relatively dark areas during the juvenile stage.     

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.     

Growth and morphological development of sagittal otoliths of larval and early juvenile Trachurus japonicus

The daily periodicity of growth increment formation in sagittal otoliths of jack mackerel Trachurus japonicus was validated by marking otoliths with alizarin complexone (ALC). Analysis of otoliths of known‐age juveniles confirmed that the first increment formed on day 3 after hatching, and was associated with first feeding. A total of 198 specimens, ranging from 2·6 to 49·2 mm in body length (notochord length or standard length) and from 7 to 78 days in age, were collected in the East China Sea and Tosa Bay, and used to examine the association between otolith morphological development and ontogenetic development. The relationship between body length ( L ) and otolith radius ( R ) was significantly described by the linear function L  = 2·65 + 0·0425 R ( n  = 198, r ² = 0·99, P  < 0·001), indicating that somatic growth history can be reconstructed from otolith growth patterns. The otolith was primarily spherical in the preflexion larval stage, and became elongated with notochord flexion. The first secondary primordium formed at c . 25 days, during the middle postflexion stage, and was associated with metamorphosis. By c . 42 days the sagittal otolith was adult‐like in morphology, with the primary growth zone enclosed by the marginal growth zone, except in the anterior rostrum area. Thus age, growth and developmental stages were recorded in sagittal otoliths during the larval and early juvenile stages of jack mackerel.     

Growth and morphological development of laboratory-reared larval and juvenile climbing perch <Emphasis Type="Italic">Anabas testudineus</Emphasis>

Morphological development, including fin and labyrinth organ, body proportions and pigmentation, in laboratory-reared larval and juvenile climbing perch Anabas testudineus was described and behavioral features under rearing condition were observed. Body lengths (BL) of larvae and juveniles were 1.9 ± 0.1 (mean ± SD) mm just after hatching (day-0), 8.7 ± 1.3 mm on day-19, reaching 18.4 ± 2.1 mm on day-35 after hatching. Aggregate fin ray numbers attained full complements in juveniles larger than 8.3 mm BL. Preflexion larvae started feeding on day-2 following formation of the upper and lower jaws, the yolk being completely absorbed by day-7 after hatching. Teeth appeared in flexion larvae larger than 5 mm BL on day-6, with cannibalism starting shortly after and continuing with further growth. Melanophores on the body increased with growth, a large dark spot developing on the lateral midline around caudal margin of the body in the postflexion and juvenile stages. The labyrinth organ differentiated in postflexion larvae larger than 7.2 mm BL on day-16, with air-breathing starting at the same time. Body proportions attained constant in postflexion larvae larger than 7.0 mm BL, and habitat of fish shifted from bottom to mid-layer. With the exception of fin ray numbers, the above morphological developments corresponded to behavioral shifts that occurred in the postflexion stage (ca. 7 mm BL), their subsequent continuity illustrating that the species possessed most juvenile-equivalent functions from ca. 7 mm BL.     

Morphometric development in laboratory-reared larval and juvenile Puntioplites proctozysron (Cypriniformes: Cyprinidae)

Ichthyological Research - Several morphometric characters with observing general morphology of laboratory-reared larval and juvenile Puntioplites proctozysron (9–40-day-old, 6.8 to...     

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.     

Growth and morphological development of laboratory-reared larvae and juveniles of the Laotioan indigenous cyprinid Hypsibarbus malcolmi

The morphological development, including the pigmentation, body proportions, fins, and survival rate for 30 days after hatching, of laboratory-reared larval and juvenile Hypsibarbus malcolmi is described. Body lengths (BL) of larvae and juveniles were 2.0 ± 0.2 (mean ± SD) mm at 1 h after hatching (day 0) and 9.2 ± 0.6 mm on day 16, reaching 12.1 ± 0.9 mm on day 30. Yolk volume decreased linearly, with the yolk being completely absorbed by day 3 in all preflexion larvae (all specimens >3.2 mm BL). Feeding was observed on day 2 in fish which had rapidly undergone complete yolk absorption following mouth and anus opening on day 1, and on day 3 in all remaining fish. Myomere numbers were 20–21 + 11–12 = 31–33, although they were not clearly visible in juveniles. Melanophores were few on the body during days 0–2, but increased with growth and covered the entire upper dorsal body surface during the juvenile stage. Body proportions tended to become constant in juveniles. Notochord flexion began in larvae >5.2 mm BL on day 8, and was completed in larvae >8.4 mm BL on day 14. Specimens with full fin ray complements were initially observed on day 22 (10.4 mm BL in juveniles). All specimens >11.5 mm BL had attained the juvenile stage. A high survival rate of 92.7% was estimated on day 30.     

Inheritance of trunk coloration in the three-spot gourami, Trichogaster trichopterus Pallas

Trunk coloration in Trichogaster trichopterus Pallas is controlled by two autosomal loci acting in a complementary fashion with dominance at both loci required for the expression of the blue sumatranus phenotype.     

Growth and morphological development of larval and juvenileepinephelus bruneus (perciformes: Serranidae)

The growth and morphological development of larval and juvenileEpinephelus bruneus were examined in a hatchery-reared series. Average body length (BL) of newly-hatched larvae was 1.99 mm, the larvae growing to an average of 3.96 mm by day 10, 6.97 mm by day 20, 12.8 mm by day 30, 22.1 mm by day 40 and 24.7 mm by day 45 after hatching. Newly-hatched larvae had many mucous cells in the entire body epidermis. By about 4 mm BL, the larvae had developed pigment patterns peculiar to epinepheline fishes, including melanophores on the dorsal part of the gut, on the tips of the second dorsal and pelvic fin spines, and in a cluster on the ventral surface of the tail. Spinelets on the second dorsal and pelvic fin spines, the preopercular angle spine and the supraocular spine, had started to develop by about 6 mm BL. The notochord tip was in the process of flexion in larvae of 6–8 mm BL, by which time major spines, pigments and jaw teeth had started to appear. Fin ray counts had attained the adult complement at 10 mm BL. After larvae reached 17 mm BL, elements of juvenile coloration in the form of more or less densely-pigmented patches started to appear on the body. Squamation started at 20 mm BL. Major head spines had disappeared or became relatively smaller and lost their serrations by 20–25 mm BL.     

Reproductive biology of the tropical fish Trichogaster pectoralis (Regan)

The breeding cycle of an air-breathing Anabantid, Trichogaster pectoralis was studied in Malaysia. The species was found to breed all the year but with pronounced peaks of activity associated with the two wetter periods in the year. The advantages of this timing and the cues which stimulate gonadal activity are discussed. From the study of oocyte distribution in selected ovaries it was concluded that T. pectoralis is a total spawner although a batch of ripe oocytes may be released over an extended period of time. Fecundity was found to be related to length of fish by the formula (log₁₀ Egg no.)=–4.6854+4.3080 log₁₀ standard length (S.L.) (mm).     

Isolation and characterisation of a serum lectin from blue gourami, Trichogaster trichopterus (Pallus)

A novel lectin, designated BGL, has been purified from the serum of blue gourami, Trichogaster trichopterus, with the use of (NH4)2SO4 fractionation, affinity chromatography and gel filtration chromatography. Electrophoretic analyses and mass spectrometric study of purified BGL showed that the lectin is composed of two isoforms with native molecular masses estimated to be 65 and 66 kDa, and two subunits of 32 and 34 kDa on SDS-PAGE under non-reducing conditions. Upon reduction with 20 mM dithiothreitol (DTT), BGL showed two close bands of 27 and 29 kDa. After isoelectric focusing, the lectin focused as close double bands at pH 5.6. The N-termini of both isoforms share the same sequence (HGEENRXGPR) and show no significant homology with any known proteins. The BGL agglutinating activity is specifically inhibited by N-acetyl-D-galactosamine and N-acetyl-D-glucosamine, and to a lesser degree by D-(+)-mannose, but not by D-(+)-galactose, D-(+)-glucose, maltose or N-acetyl-D-mannosamine. Haemagglutination assay showed that BGL is more specific for rabbit than mouse, chicken, rat or guinea pig erythrocytes, and haemagglutination was Ca2+-dependent. In addition, BGL could agglutinate a range of micro-organisms and yeast cells, with the exception of some fish pathogens, such as Aeromonas hydrophila (strains: PPD 134/91 and PPD 11/90) and Vibrio harveyi (strain: W618). Localisation of BGL by fluorescein isothiocyanate (FITC)-labelled antibodies revealed that the lectin is associated with the cell surface of fish leukocytes.     

Oxidation of fatty alcohols to acids in the caecum of a gourami (Trichogaster cosby).

Oxidation of fatty alcohols to acids in gourami caeca was investigated by measuring the reduction of NAD+ and the formation of labeled hexadecanoic acid from [1(-14)C]hexadecanol. Virtually all dehydrogenase activity is in the microsomal fraction. Maximal activity is obtained with NAD+ as cofactor whereas with NADP+ 60% of that activity is obtained. The enzyme is rather specific for long chain alcohols and 2 NADH are formed for each molecule of hexadecanol oxidized to acid. It is stabilized by mercaptoethanol, and completely inhibited by p-chloromercuribenzoate. The activity is optimal at pH 9.5. At higher pH, small amounts of aldehyde are found. The first reaction in the sequence, fatty alcohol leads to aldehyde leads to acid seems to occur under the more physiological condition at a much slower rate than the second reaction so that free aldehyde is not detected. Addition of palmitic acid indicated an uncompetitive product inhibition. The oxidation of alcohol to acid is reversible only to a very minor extent even in the presence of NADPH, CoA, ATP and Mg2+. Location, activity and properties of the enzyme are in agreement with the earlier observation from dietary experiments that in the gourami fatty alcohols of wax esters are oxidized to acids in the course of absorption.     

Metabolism of oleic, linoleic and linolenic acids in gourami (Trichogaster cosby) fry and mature females.

1. Female gouramis incorporated pulse-fed [U-14C]oleic, linoleic and linolenic acids more readily into roe than body lipids. Labeling was highest in eggs spawned 20-30 days after feeding. 2. In the fry, linoleic and linolenic were catabolized more slowly than oleic acid, indicating conservation of the polyunsaturated acids in the early stage of life. 3. In the mature female, metabolism of linolenic was distinct from that of the other acids by more extensive conversions and greater use of 14C for de novo synthesis of fatty acids.     

Growth of larval and juvenile perch: the importance of diet and fish density

In August, growth rate of young–of–the–year (YOY) Perch In lake enclosures could be explained by both YOY density and mean cladoceran biomass, suggesting that in a lake where YOY perch are dominant, growth may be density dependent in late summer and mediated through top–down control on daphnid biomass. In June, growth rate of YOY perch could not be fully explained by YOY density or by mean cladoceran biomass, suggesting that growth and survival during the first part of the summer is negatively affected by a diet of Bosmina and cyclopoid copepods only. The experiments also suggest why YOY perch have a slow growth and a low abundance in eutrophic lakes where small zooplankton dominate. The June experiment also indicated that growth of late larval or early juvenile perch improved when a larger cladoceran became available and was included in the diet.     

Temporal changes in fat and protein levels in the tropical Anabantid Trichogaster pectoralis (Regan)

Samples of a wild population of the Anabantid Trichogaster pectoralis (Regan) were taken during and after one of the two main breeding periods of the year. Carcasses of both sexes and female gonads were analysed for fat, protein and carbohydrate. Carbohydrates were present in insignificant amounts in all tissues. The fat content of the ovary proved to be high (over 30% of wet weight) and, as a result, ovarian energy in a ripe female formed a substantial proportion of the total energy content of the fish. However, it did appear possible for females to develop large ovaries without depleting the carcass fat stores.
Although protein levels in the carcass were significantly higher in 1 month, relative to fat levels, protein levels remained fairly constant during the period of study. Conversely fat levels showed marked fluctuations throughout the breeding period, being high at the start of the breeding period, low towards the end, finally rising again 1 month after most fish had terminated breeding. The range of fat levels appeared to be independent of the gonadal state of the fish at capture and seemed more closely related to month of capture. Two explanations are suggested; (1) changes in food availability over the period in question and/or (2) if repeated spawnings occur this could deplete fat reserves in the carcass.
In this species fat is stored largely in the muscle but some is stored around the coiled intestine. A visual scoring system was used to assess the extent of this fat deposition and it was found that the fat score was correlated with the level of fat in the carcass. Thus the level of fat around the intestine, although insignificant relative to carcass fat, could be used as a method of assessing the fatness of a fish.     

Effect of environmental temperature on growth- and reproduction-related hormones gene expression in the female blue gourami (Trichogaster trichopterus)

Fish are ectothermic vertebrates, and their gonadal development and spawning are affected by changes in environmental temperature. Recent global temperature changes have increased the importance of studying the effect of temperature on reproduction. The aim of this paper was to study the effect of temperature on oogenesis and hormone gene expression related to reproduction and growth in the blue gourami female maintained under non-reproductive and reproductive conditions. In females under non-reproductive conditions, vitellogenic oocytes, gonadotropin-releasing hormone 3 (GnRH3), β luteinizing hormone (βLH) and growth hormone (GH) mRNA levels were affected by temperature changes. In females maintained under reproductive conditions with non-reproductively active males, a percentage of females in the final oocyte maturation (FOM) stage, pituitary adenylyl cyclase activating polypeptide (PACAP and PRP-PACAP), gonadotropins and GH mRNA levels were affected due to temperature changes. In females maintained under reproductive conditions with reproductively active males, also GnRH3 and insulin-like growth factor 1 (IGF-1) were affected by temperature changes. In conclusion, in blue gourami females, changes in environmental temperature affect oogenesis through changes in brain and pituitary hormone mRNA levels.