Dwarf Gourami Research Articles

Iridovirus-like virions in imported dwarf gourami (Colisa lalia) with systemic amoebiasis.

Iridovirus-like virions in imported dwarf gourami (Colisa lalia) with systemic amoebiasis.

Ultrastructural characterization of gonadotropin-releasing hormone (GnRH)-immunoreactive terminal nerve cells in the dwarf gourami

Recently we have been studying gonadotropin-releasing hormone (GnRH) cells of the terminal nerve (TN) in the dwarf gourami, which may serve as a good model system for the study of neuromodulator functions. Here we report on the ultrastructural characterization of TN-GnRH cells using postembedding immunoelectron microscopy. The GnRH immunoreactivities could be demonstrated on dense-cored vesicles (DCVs) in cell bodies, fibers and varicosities. However, we could find no evidence of GnRH-immunoreactive synapses which are characterized by active zones. This may suggest that GnRH is released non-synaptically from DCV-containing fiber varicosities and that it exerts its modulatory action on GnRH receptors located on nearby as well as distant target neurons.

Pesticide-induced atresia in ovary of a fresh water fish, Colisa lalia (Hamilton-Buchanan).

Pesticide-induced atresia in ovary of a fresh water fish, Colisa lalia (Hamilton-Buchanan).

Ultrastructure of the ganglion cells of the terminal nerve in the dwarf gourami (Colisa lalia)

In our previous light microscopic studies (Oka et al., Brain Res. 367: 341-345, '86; Oka and Ichikawa, J. Comp. Neurol. 300: 511-522, '90), we reported that there are at least two types of terminal nerve (TN) cells based on cell size and immunoreactivity: type I cells had large cell bodies, while type II cells had smaller cell bodies. Type I TN cells were immunoreactive to gonadotropin-releasing hormone (GnRH) and may be the major source of GnRH-immunoreactive fibers that are widely distributed throughout the brain. Type II TN cells, on the other hand, were not immunoreactive to GnRH. In the present paper, we examined the cytology and synaptology of these two types of TN cells with electron microscopy. Type I TN cell bodies were found to have morphological characteristics similar to those of other peptide-synthesizing neurons and are likely to be actively synthesizing GnRH. The frequent occurrence of coated vesicles close to the plasma membrane of the cell body was suggestive of membrane retrieval following exocytosis of the vesicular contents from the cell surface. Neighboring TN cells were either in direct juxtaposition with one another or made specialized "glomeruloid" cell-to-cell contacts; these specializations may be relevant for nonsynaptic intercellular communications among the TN cells. Within these glomeruloid complexes, the somatic processes of TN cells received inputs from two types of synaptic terminals: one containing only spherical synaptic vesicles and another containing a small number of dense-cored vesicles in addition to the spherical synaptic vesicles. Axosomatic synapses were rare on type I TN cell bodies. In contrast, type II TN cell bodies had morphological characteristics similar to those of neurons in other brain regions. These receive axosomatic inputs from synaptic terminals containing only spherical synaptic vesicles and those with a small number of dense-cored vesicles in addition to the spherical synaptic vesicles. Thus, each type of TN cell has unique fine structural characteristics which may correlate to their different functional roles.

Intracellular recording and staining of terminal nerve cells in the brain of the dwarf gourami in vitro

Intracellular recording and staining of terminal nerve cells in the brain of the dwarf gourami in vitro

Gonadotropin‐releasing hormone (GnRH) immunoreactive system in the brain of the dwarf gourami (Colisa lalia) as revealed by light microscopic immunocytochemistry using a monoclonal antibody to common amino acid sequence of GnRH

The present paper aims to give a morphological basis for the study of the terminal nerve system and its relation to the whole gonadotropin-releasing hormone (GnRH) immunoreactive (ir) neuronal system. We examined the GnRH-ir neuronal system of a tropical fish, the dwarf gourami, by using a recently developed monoclonal antibody against GnRH (LRH13) which recognizes the amino acid sequence common to all known variants of GnRH (Park and Wakabayashi, Endocrinol. Jpn. 33:257-272, '86). The ganglion cells of the terminal nerve (TN-ggl cells) in the transitional area between the olfactory bulb and the telencephalon reacted strongly with the LRH13. A distinct bundle of axons emanating from the TN-ggl cells ran caudally through the ventral telencephalon and the preoptic area. Some of these axons entered the optic nerve and innervated the retina. The remaining axons continued caudally to enter the hypothalamus and the midbrain. A second group of GnRH-ir cell bodies was found in the preoptic area. A distinct bundle of GnRH-ir fibers originating from these cell bodies innervated the pituitary. This pathway is equivalent to the preoptico-infundibular pathway of other vertebrates, and the GnRH in this pathway is presumed to function as hypophysiotrophic hormone to facilitate the release of gonadotropins from the pituitary. The distribution of GnRH-ir fibers in the brain was extensive. Most fibers apparently originated from the TN-ggl cells and covered various brain regions from the olfactory bulb to the spinal cord. They were especially abundant in the olfactory bulb, ventral telencephalon, preoptic area, optic tectum, and some hypothalamic areas. Thus, GnRH might function as a neuromodulator and/or neurotransmitter in these areas. The abundant GnRH-ir fibers in the ventral telencephalon and the preoptic area might affect some aspects of sexual behavior, since these areas have been suggested to be involved in the control of sexual behavior in teleosts.

The Volume of Air Within the Swimbladder and Breathing Cavities of the Anabantoid Fish Colisa Laua (Perciformes, Belonthdae)

ABSTRACT The swimbladder volume and air volume within the breathing chambers of the anabantoid fish Colisa lalia have been measured. These data help in the understanding of some of the functions of these organs and are necessary for an analysis of their role in hearing and sound production. By means of a simple trick (based on new data) it was possible to analyse the time course of air volume changes in the breathing chambers at different temperatures. The results are well described by a simple diffusion model. The temperature-dependence of the time course suggests an interesting increase of the diffusion constant with temperature. Under constant conditions the chambers were always filled with about the same volume of air. No excess pressure was found. Typical values of a single chamber’s air content range from 34 to 58 μl. Air content increases with about the third power of fish length. By using the present data, the time course of air volume changes in the chambers of a given fish can be estimated. Swimbladder volumes, determined using Boyle’s law, ranged from 70 to 220 μ1 and were also found to increase with about the third power of fish length, in accordance with a simple estimation. The data are discussed in relation to buoyancy, diffusion processes, blood circulation, hearing and sound production and suggest some interesting new work.

Culture of the Dwarf Gourami Colisa lalia in Singapore

Culture of the Dwarf Gourami <i>Colisa lalia</i> in Singapore

Use of cover and the need to breathe: the effects of hypoxia on vulnerability of dwarf gouramis to predatory snakeheads

The behavior of dwarf gouramis (Colisa lalia, Pisces, Belontiidae) and their vulnerability to predation by snakeheads (Channa micropeltes, Pisces, Channidae) were observed at four dissolved oxygen concentrations. When the oxygen level was near saturation (8 ppm) or only moderately reduced (3 ppm), the gouramis rarely breathed air and spent most of their time in a patch of artificial vegetation. At extremely low oxygen concentrations (1 and 0 ppm) the gouramis increased their air-breathing frequency and spent less time in cover. Gouramis were more likely to be captured by the snakeheads when out of the vegetation, and thus were caught more quickly at lower oxygen levels, even though their air-breathing frequency declined and use of cover increased in the presence of the predators. These results indicate that dissolved oxygen concentration, which varies considerably in many fish habitats, can affect use of cover and risk of predation in fishes.

Retinopetal projections from a subpopulation of ganglion cells of the nervus terminalis in the dwarf gourami ( Colisa lalia)

The ganglion cells of the nervus terminalis (NT cells) of the dwarf gourami could be classified into type I (giant) and type II (medium to large) cells. After unilateral application of cobaltic-lysine to the optic nerve, only the type II NT cells on the contralateral side were retrogradely labelled. The dendrites ramified near the cell bodies and invaded the olfactory bulb. The axons ran caudally, while taking dorsal and ventral courses, through the ventral telencephalon and the lateral preoptic area, and entered the optic tract.

Localization of prolactin uptake by the kidney of the teleostean, Colisa lalia

Although evidence has been presented that the hormone prolactin specifically binds to the kidneys of the teleost Sarotherodon mossambicus ( J. N. Fryer, 1979, Gen. Comp. Endocrinol. 39, 397–403.) prolactin has not previously been shown to become localized at any particular morphological sites in fishes. This problem has been investigated in the dwarf gourami, Colisa lalia. Ovine prolactin was labeled with 125I and injected intramuscularly. Fish were sacrificed after 15, 30, and 90 min. Other animals were injected with an excess of unlabeled prolactin, growth hormone, or luteinizing hormone 2 min prior to administration of the label. Paraffin-embedded tissues were sectioned, coated with Kodak NTB-3, and exposed for 3–5 weeks. After developing, samples of several body tissues were stained and examined for the presence of silver grains. The results indicate that, as in rat and frog, kidney tubules of C. lalia are sites of prolactin localization. No other sites of prolactin localization were identified.

Multiple matings and sexual dichromatism in the dwarf grourami, Colisa lalia

Multiple matings and sexual dichromatism in the dwarf grourami, Colisa lalia

Kinetics of dose-response relationship in the bimodal respiration of Colisa lalia (Hamilton-Buchanan) exposed to lindane (γ-BHC)

Acute bioassay tests were conducted with the organochlorine pesticide, lindane on Colisa lalia. LC50 and its 95% upper and lower confidence limits for different periods of exposure were determined. A toxicity curve was constructed from which is derived the lethal threshold concentration for Colisa to lindane. The fish were exposed to two selected concentrations viz., 0.1 and 0.37 mg 1 −1 for 96 and 6 h respectively and their behaviour and bimodal respiration were studied. Erratic behavioural responses were noticed at 0.37 mg 1 −1 whereas the response at 0.1 mg 1 −1 were orderly and adaptive. Total oxygen consumption of fish increased but the dependence on the type of respiration differed in the two concentrations, and this selective dependence at 0.1 mg 1 −1 is suggested to have survival value.

Effects of prolactin on the kidney of a teleostean fish: Transmission electron microscopic observations

Mammalian prolactin (PRL) was previously found to be toxic to the dwarf gourami, Colisa lalia. In an effort to identify the cause of the PRL toxicity, kidneys of fish treated with the hormone were examined by transmission electron microscopy. At the ultrastructural level many degenerating cells, characterized by nuclear fragmentation, cytoplasmic dissolution, and pyknosis, were seen in the renal tubules. A variety of profiles of crystalline bodies were present in the interstitial tissue. Neither crystalline bodies nor degenerating cells were seen in kidneys from control animals. These findings provide a clear indication that the kidney is at least one of the primary sites of the PRL toxic effect.

Using the Blue Gourami in Ethological and Embryological Studies

Laboratory experiments on repro duction and embryological development traditionally use frogs or toads (Ben-Gal 1974). We suggest the use of the blue gourami, Trichogaster trichopterus (Pisces, Belontiidae) as an alternative subject in such experiments. The blue gourami is a member of a family of tropical fishes (Belontiidae) with many well-known representatives, including the Siamese fighting fish (Betta splendens), the paradise fish (Macropodus opercularis), and the dwarf gourami (Colisa lalia). Because it is an air breathing-fish native to the stagnant rice paddies and temporary swamps of South East Asia, no aeration equipment is required. Blue gouramis are easily bred in the laboratory, and they provide thousands of eggs throughout the year. Breeding need not be induced by the administration of exogenous hormones as with most amphibian preparations. The numerous advantages of using blue gourami eggs for embryological demonstrations include the following:

Belontiidae chemosignal activity: interspecific attraction and perceived chemosignal similarity

Belontiidae chemical communicatory substances were examined for interspecific behavioral activity. In Experiment 1, male Betta were exposed to ripe-female-conditioned water (RFCW) from either the goldfish (Carassius auratus) or one of the following Belontiidae species: (a) Betta splendens, (b) Colisa labiosa, (c) Colisa lalia, (d) Macropodus opercularis, or (e) Trichogaster trichopterus. Time spent near and within a stimulus source tube was used to measure the chemosignal activity for each species. Both behavioral measures showed evidence for interspecific chemocommunication. The proximity measure indicated a phylogenetically nonspecific chemosignal, whereas tube occupancy indicated the presence of a specific Belontiidae system. Experiment 2 was a stimulus generalization test using a psychophysical paradigm. Male Betta were trained to discriminate Betta RFCW from Carassius RFCW, and were subsequently presented with RFCW from either (a) C. lalia, (b) M. opercularis, (c) T. trichopterus, and (d) P. reticulata. The latter were novel stimulus generalization chemosignals. The male Betta perceived Belontiidae RFCW stimuli as similar, whereas guppy RFCW was neither perceived as Belontiidae nor Carassius RFCW. Thus, Belontiidae chemosignals may be similar in structure due to a common phylogenetic ancestry.

Toxic effects of mammalian prolactin on Colisa lalia and two other related teleostean fish

Mammalian prolactin has been found to have a highly toxic effect on certain teleostean fish. The effect is not due to contamination by growth hormone or ADH, nor is the toxic factor removed by dialysis. The toxic effect is dependent upon type and activity of the prolactin as well as upon the species, and perhaps the size, of the fish. Possible reasons for the toxic action are discussed.

A note on the potential applicability of malachite green oxalate in combating fish-mycoses

In the present investigations the potential fungicidal ability of malachite green oxalate has been tested in vitro on four fish-pathogenic isolates of Saprolegniaceous fungi viz.,Saprolegnia ferax (Gruith) Thuret,Achlya flagellata Coker,Aphanomyces laevis De Bary andIsoachlya anisospora var.indica Saxena and Bhargava and the lowest concentration having fungicidal ability has been found to be 0.5 ppm. Tolerance tests have also been conducted usingPuntius sophore, Colisa lalia, Anabas testudineus andCatla catla as test fishes. Also the applicability of the lowest fungicidal concentration of this chemical (i.e. 0.5 ppm) in sustained culturing of the adult individuals ofCatla catla, a major food fish, against the mycotic infection, has been tested.

Host range of Achlya prolifera (Nees) de bary on certain fresh water teleosts

Host range of Achlya prolifera (Nees) De Bary has been extended to Cotisa fasciatus, Colisa lalia, Puntius sophore, Notopterus chitala, and Anabas testudineus by conducting artificial inoculation experiments under controlled laboratory conditions.

Isolation of pathogenic bacteria from the skin ulcerous symptomatic gourami (&lt;i&gt;Colisa lalia&lt;/i&gt;) through 16S rDNA analysis

Aeromonas spp infections are probably the most common bacterial disease diagnosed in cultured warm water fish. In the present study, six strains of Aeromonas spp bacteria were isolated from the gourami (Colisa lalia) by 16S rDNA sequencing analyses that are pathogenic to freshwater fish. Among them, three were under Aeromonas veronii species, two were Aeromonas sp ATCC and one was Aeromonas hydrophila. Colisa lalia usually imported in Korea from the South and South-east Asian countries for recreational purposes. However, they are playing important role as a disease vector or carriers. The infected fish of this study frequently have hemorrhages at the base of the fins or on the skin, and gross ulcerative lesions. Internal signs include, fluid in the abdomen, swollen liver and spleen, and the intestine was distended and fluid-filled. In this study, the utility of 16S rDNA sequencing was employed to isolate Aeromonas bacteria from freshwater imported fish are important to environment, veterinary, and clinical purposes. Key word: Bacteria, Colisa lalia, 16S rDNA, Aeromonas  doi:10.3329/ujzru.v27i0.1948 Univ. j. zool. Rajshahi Univ. Vol. 27, 2008 pp. 21-24