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Synthetic hormones are widely used for induced breeding with significant successes. This study compared spawning successes in paradise fish (Macropodus opercularis) using synthetic hormone (Ovaprim) and natural simulation in glass tanks (0.3m x 0.6m). The experiment was conducted in two parts using two males and two females brood fish. The weights of the fish were between 4.0 and 5.0g for the males and 5.0 and 6.0g for the females. For the induced spawning, Ovaprim was injected intramuscularly according to the fish body weight after which they were left to spawn. The group on natural spawning were not induced by any hormone. Hatching of the eggs occurred within 48 hours at a temperature of 28.80C. Total number of eggs obtained by artificial and natural breeding were 430 and 322eggs respectively. Percentage fertilization in artificial breeding was 63.26% while 41.93% was recorded in natural breeding. Fry were raised on compounded diet for 6 weeks. Results showed that artificially bred fish had a higher mean weight gain (2.31 g) and survival rate (48.17%) than those from natural breeding having 2.10 g and 44.26% respectively. The results suggest that artificial breeding using synthetic hormone (Ovaprim) yielded better spawning success and survival rate than natural process. Keywords: Paradise fish, natural breeding, hormone, fertilization, survival

Macropodus opercularis (Linnaeus) (Fig. 111, EAs[SPC]) References. Tan et al., 2013. Distribution. Bukit Brown (Tan et al., 2013). Remarks. This species is sometimes sold as live feed in the ornamental fish trade (Tan HH, pers. obs.)., Published as part of Hui, Tan Heok, Peng, Kelvin Lim Kok, Huan, Liew Jia, Wei, Low Bi, Hing, Rayson Lim Bock, Beng, Jeffrey Kwik Teik & Yeo, Darren C. J., 2020, The non-native freshwater fishes of Singapore: an annotated compilation, pp. 150-195 in Raffles Bulletin of Zoology 68 on page 183, DOI: 10.26107/RBZ-2020-0016, http://zenodo.org/record/5343987, {"references":["Tan JYH, Tan LHC, Quek G, Lim VSF & Tan HH (2013) The fish fauna of Bukit Brown, Singapore. Nature in Singapore, 6: 229 - 237."]}

The round-tailed paradise fish (Macropodus ocellatus) is important to the local ecosystem and economy. Other species in the genus Macropodus are undergoing population declines, indicating that the M. ocellatus population might also be declining. Therefore, the status of M. ocellatus, related to standing-water ecosystem stability and sustainable utilization of fishery resources, requires attention. In this study, we assessed the spatial pattern of the M. ocellatus genetic structure in 10 localities from China. Sequencing of Cytb (1135 bp) and the D-loop (668 bp) yielded 26 and 10 haplotypes, respectively. A total of 30 haplotypes were identified among 165 concatenated mitochondrial DNA sequences. The results showed that the total haplotype diversity of the 10 populations is high (0.910) and that genetic diversity indices for sequences from HuaiAn were the highest (haplotype diversity Hd = 0.780, nucleotide diversity pi = 0.00363). The results of AMOVA indicated that most genetic variation was among populations within groups (80.22%, P

Adults of Paradise fish Macropodus opercularis are easily maintained in the laboratory. The fertilized eggs of Paradise fish were natural inseminated and incubated in room temperature (range 22.5 to 25.7°C). We carefully observed the process of embryonic development and divided them into 28 stages based on diagnostic features of the developing embryos. The principal diagnostic features are the number and size of blastomeres, form of the blastoderm, extent of epiboly, development of the central nervous system, number and form of somites, optic and otic development, heart development, blood circulation, the size and movement of the body, and development of the tail.

It has hitherto been unknown whether the paradise fish Macropodus opercularis that inhabits the Ryukyu Archipelago, Japan, is native to the region or was introduced. This study examined the genetic identity of fish from five islands in the Ryukyu Archipelago (Okinoerabu, Okinawa, Yagaji, Kume, and Minamidaito islands) and compared it with those from Taiwan Island, mainland China, and Hainan Island. Analyses of the mtDNA control (760 bp) and cytb (660 bp) regions showed that haplotypes of specimens from the Ryukyu Archipelago were the same as or were very similar (with a 1- or 2-bp difference) to those from Taiwan. In addition, haplotypes from the Ryukyu Archipelago also showed lower genetic diversity than those from Taiwan Island, mainland China, and Hainan Island. These results suggest a high likelihood that the fish in the Ryukyu Archipelago were artificially introduced from Taiwan. However, the possibility that the fish is indigenous to the Ryukyu Archipelago cannot be completely ruled out, because some haplotypes and a clade from the Ryukyu Archipelago have not been found in the other areas. Regardless of its origin, we emphasize the importance of the conservation of the paradise fish in the Ryukyu Archipelago as an indicator of the threatened wetland environment as well as for its cultural value.

Thanks to its small size, external fertilization and fecundity, over the past four decades, zebrafish (Danio rerio) has become the dominant fish model species in biological and biomedical research. Multiple lines of evidence, however, suggest that the reliance on only a handful of genetic model organisms is problematic, as their unique evolutionary histories makes them less than ideal to study biological questions unrelated to their historically contingent adaptations. Therefore, a need has emerged to develop novel model species, better suited for studying particular problems. The paradise fish (Macropodus opercularis) has a much more complex behavioral repertoire than zebrafish and has been a favored model animal in ethological research during the last decades of the previous century. We believe that with currently available, easily adaptable genetic toolkits, this species could be easily developed into a popular model of behavioral genetics. Despite its earlier popularity, however, the description of a detailed housing and husbandry protocol for this species is still missing from scientific literature. We present here a detailed description of how to raise and breed paradise fish successfully under laboratory conditions, and also discuss some of the challenges we faced while creating a stable breeding population for this species in our facility.

The aggressive behavior of male paradise fish (Macropodus opercularis) was studied. Fish were subjected to three aggressive encounters on consecutive days. If submissive males encountered the same opponent three times, the last aggressive encounter was very different than the first one. When the animals faced a new opponent each day, the changes were much less pronounced. We conclude that (1) fish are able to recognize their opponents at least one day after the encounter ("social recognition"), and (2) social recognition modifies the effect of prior defeat ("status-related memory") in subsequent encounters.

Aquatic air-breathing anabantoids, a group of fish species characterized by the presence of a labyrinth organ and some gills, exhibit morphological variations. This study aimed to examine whether unequal gill growth begins during the early stages and described the sequence of the early gill developmental events in Betta splendens and Macropodus opercularis. To determine when the ion regulatory and gas exchange abilities first appear in the gills, mitochondria-rich cells (MRCs) and neuroepithelial cells (NECs) were examined in young B. splendens. To evaluate the relative importance of the gills and the labyrinth organ under different levels of oxygen uptake stress, the levels of carbonic anhydrase II (CAII) and Na(+)/K(+)-ATPase (NKA) protein expressions in 2 gills and the labyrinth organ were examined in M. opercularis. We found that the first 3 gills developed earlier than the 4th gill in both species, an indication that the morphological variation begins early in life. In B. splendens, the MRCs and NECs clearly appeared in the first 3 gills at 4 dph and were first found in the 4th gill until 11 dph. The oxygen-sensing ability of the gills was concordant with the ionoregulatory function. In M. opercularis, the hypoxic group had a significantly higher air-breathing frequency. CAII protein expression was higher in the labyrinth organ in the hypoxic group. The gills exhibited increased NKA protein expression in the hypoxic and restricted groups, respectively. Functional plasticity in CAII and NKA protein expressions was found between the gills and the labyrinth organ in adult M. opercularis.

Axenic cultures of two moss taxa viz. Bryum dichotomum Hedw., an acrocarpous moss and Entodon macropodus (Hedw.) Mull. Hal., a pleurocarpous moss were established by inoculating their spores into agar media. Germination, growth, development and comparative morphogenetic studies of these two growth forms were done. In B. dichotomum, protonemal buds developed on caulonema, while in E. macropodus, buds were produced on chloronema. Sub culturing of B. dichotomum gave rise to new individuals through chloronemal and caulonemal stage, while E. macropodus it directly regenerated into new gametophytes. In old culture under low moisture conditions, asexual diaspores namely, protonemal bulbils B. dichotomum and protonemal brood cells E. macropodus were formed.

Iridoviruses are large DNA viruses that are subdivided into five genera: Ranavirus, Megalocytivirus, Lymphocystivirus, Chloriridovirus and Iridovirus. The iridovirus lymphocystis disease virus (LCDV) is an important fish pathogen that can infect marine and freshwater fish worldwide. In this study, we have identified the pathogen in paradise fish (Macropodus opercularis) with lymphocystis. On the skin and fins of diseased paradise fish, a large number of nodules were observed. H&E staining showed that the nodules were composed of encapsulated hypertrophied cells. Using electron microscopy, numerous virus particles with a diameter of >210 nm and with hexagonal profiles were observed in the cytoplasm. Phylogenetic analysis based on the major capsid protein (MCP), DNA polymerase and myristylated membrane protein (MMP) genes revealed that LCDV from paradise fish (LCDV-PF) was closely related to lymphocystis disease virus from China (LCDV-C), followed by lymphocystis disease virus 1 (LCDV-1). Taken together, our data provide the first molecular evidence that, in addition to megalocytivirus, LCDV is an important iridoviral pathogen in paradise fish besides megalocytivirus.

We report on mycobacteriosis in an imported tropical ornamental fish Macropodus opercularis commonly known as the paradise fish. Mass mortality occurred in paradise fish imported to Korea from Southeast Asia in 2008. The affected fish did not show any outward clinical signs, but enlargement of the spleen, kidneys, and liver was observed on dissection. Histopathological examination revealed numerous granulomas in the spleen, and acid-fast bacilli were observed in the centers of the granulomas. About 65% of spleen DNA samples were PCR positive using mycobacteria-specific primers targeting the 16S rRNA and hsp65 genes. The nucleotide identities of the 16S rRNA and hsp65 genes with those of Mycobacterium marinum were 99.5% and 99.4%, respectively. Although the bacterium was not cultured, the molecular diagnosis and histopathological findings were consistent with mycobacteriosis in paradise fish.

Aquarium trade has been the source of many alien species being introduced into the natural waters of Chennai. Trichopsis vittata and Macropodus opercularis are being reported for the first from Chennai. However, contrary to the propagule pressure theory both these species are not common in the aquarium trade, raising speculations of inter-basin water transfer playing a role in introducing non-native species into an ecosystem.

The characteristic of fish fauna and population Zacco koreanus was investigation in the Bongseonsa Stream Gyeonggi-do, Korea from May to September 2011. The collected species during the survey period were 22 species belonging to 9 families. Among them, one species (Cottus koreanus) was classified as an endangered species in Korea. Ten species (45.5%) were endemic species of Korea. Dominant species was Rhynchocypris oxycephalus (St. 1), Zacco platypus (St. 2, 4, 5, 7), Z. koreanus (St. 3), and Squalidus gracilis majimae (St. 6). When our data were compared with the previous data (1932, 31 species) and this date (23 spcies), Anguilla japonica, Acheilognathus signifer, Hemibarbus labeo, Hemibarbus mylodon, Gnathopogon strigatus, Saurogobio dabryi, psariichthys uncirostris amurensis, Lefua costata, Pseudobagrus fulvidraco, Pseudobagrus koreanus, Oryzias sinensis, Trachidermus fasciatus, Coreoperca herzi, Siniperca scherzeri, Micropterus salmoides, Macropodus chinensis and Channa argus 17 species were not sampled, but Pseudorasbora parva, Microphysogobio yaluensis, Orthrias nudus, Silurus microdorsalis, Odontobutis platycephala, Odontobutis interrupta and Micropterus salmoides 7 species could new taxa fiend its existence at the Bongseonsa Stream. Length-weight relation in the population of Z. koreanus was BW=0.0000007TL3.03, and condition factor in the population was average 0.78. Frequency analysis of total length indicated that the group 40∼80 mm in total length is represented by one-year-old individuals, the group 90∼120 mm by two-year-old individuals, and the group over 130 mm by three-year-old individuals. This species was stabilized spawn in the Bongseonsa Stream since then introduction, 2007.

Predator recognition and avoidance by paradise fish have been studied with allopatric species and model experiments. The effect of sympatric predators has not been investigated. Here I report that reactions of paradise fish towards a sympatric predator (Channa micropeltes) are quantitatively different from those shown towards an allopatric predator or different harmless species of fishes. I investigate the possible cues eliciting this differential response and show that visual as well as olfactory stimuli play roles. Olfactory stimuli from the sympatric predator alone elicit an elevated level of activity from paradise fish; the appearance of the sympatric predator (with or without olfactory stimuli) results in an exploratory and display reaction. I speculate what visual stimuli may play roles in predator recognition in paradise fish and I suggest that previously asserted key stimuli such as the eyes of the encountered heterospecific fish may not differentiate the harmful species from innocuous. I conclude that the antipredatory behavior of paradise fish may be affected by both genetic factors and learning and that the relative importance of the former or latter factor may vary depending on the situation.

1. The behavioural patterns of the following species of the family Belontiidae were qualitatively examined and compared with each other: Colisa lalia, C. fasciata, C. chuna, Trichogaster trichopterus, T. leeri, T. microlepis, Macropodu, opercularis, Pseudosphromenus (Macropodus) cupanus cupanus, Betta splendens, Trichopsis pumilus, T. vittatus vittatus, T. vittatus schalleri, Belontia signata and the hybrids Colisa fasciata X lalia. 2. Among other points the paper puts some emphasis on the description of the reproductive behaviour of the various species (nest building, mating, parental behaviour). In addition aspects of feeding and fighting behaviour are described. 3. The subfamilies established by Liem (1963) on the basis of osteological characteristics can also be substantiated ethologically. 4. Liem's conception of the phylogeny of Belontiidae is criticized. His system conceiving phylogeny as a process of branching off successively is contrasted with a phylogenetic fan. The subfamilies Belontiinae, Trichogasterinae and Macropodinae differentiated almost at the same time. 5. The genus of Macropodus has a very isolated position within the sub-family of Macropodinae. The remaining genera are on a higher level of development regarding their reproductive behaviour. As a result of the paper Pseudosphromenus (Macropodus) cupanus has to be eliminated from the genus of Macropodus.

Zusammenfassung 1 Baustimmung last sich bei Macropodus opercularis-♂♂ durch Chorion-Gonadotropin- oder Methyl-Testosteron-Gaben hervorrufen. Sie ausert sich in erhohter Luftholfrequenz und Bauappetenz. Die Gonadotropinwirkung tritt verzogert ein, was auf einen sekundaren Einflus von Androgen hinweist. Beide Hormone regen weder die Schleimbildung in der Epidermis an, noch losen sie allein vollstandiges Nestbauen aus. Jedoch bewirkt Androgen die Ausschuttung von Sekret aus den gefullten Vakuolen der Becherzellen. Chorion-Gonadotropin und Androgen steigern gleichsinnig die Kampfbereitschaft und die gesamte Aktivitat. 2 Sauger-Prolaktin regt die Schleimbildung in der Epidermis an. Die Zunahme der Schleimvakuolen ist von der Dosis als auch von der Vakuolenzahl vor der Behandlung abhangig. ♂♂ reagieren empfindlicher auf Prolaktingaben als ♀♀, die normalerweise nicht bauen. 3 Gleichzeitige Verabreichung von Methyl-Testosteron und Prolaktin ruft bei Makropoden-♂♂ und ♀♀ Schaumnestbau hervor. Dagegen erzeugt gleichzeitige Chorion-Gonadotropin- und Prolaktin-Gabe kein vollstandiges Bauen. 4 Mit Prolaktin behandelte Makropoden benehmen sich auffallend ruhig. Ihre gesamte Aktivitat ist gedampft. Im Kampfbereich ist das Breitseitimponieren vermindert, da es teilweise sexuell motiviert ist. Die Zahl der Angriffshandlungen (Schnappen, Stosen) wird durch Prolaktin nicht verringert. Dagegen unterdruckt es bei gleichzeitiger Gabe von Chorion-Gonadotropin dessen kampfsteigernde Wirkung, was fur einen Antagonismus dieser Hormone spricht. Anderseits beeintrachtigen sich Methyl-Testosteron und Prolaktin in ihrer Wirkung auf das Kampfverhalten nicht. 5 Fur die Existenz eines „Makropoden-Prolaktins” spricht, das Reserpin, das bei Saugetieren bekanntlich Prolaktin freisetzt, genau wie Sauger-Prolaktin Schleimvermehrung in der Epidermis hervorruft. 6 Wahrscheinlich sind der schleimvermehrende und der Brutpflegefaktor des Makropoden identisch. Hierin ist wohl die Ursache fur die unterschiedlichen Verhaltensphasen im Fortpflanzungszyklus des „Fremdmaterialbauer-” und des „Schaumnestbauer-Typus” zu suchen.

The ontogeny of antipredator behaviour of paradise fish was examined using a simple testing method. The results showed that the ability to recognize eyespots appears in larvae between 15 and 20 days old. At the same time, two horizontally placed eyespots produced the most pronounced effect on the behaviour of the larvae. Testing different inbred strains revealed that the ontogeny of antipredator behaviour is also under broad genetic control, as the response to a model predator was strong in one strain but weak in another. The results suggest that the recognition of eyespots coincides with larvae becoming more conspicuous to predators by the appearance of pigmentation and increasing level of swimming activity (exploration).

The behaviour of the paradise fish in the presence of either a living pike or catfish or various dummies or a catfish equipped with a pair of artificial big eyes was studied. Analyzing the first encounter two separate periods of the predator recognition process could be identified. The primary form of the antipredatory reaction was orientation (looking at the object while keeping a constant eye and body position) which was elicited by any fish-like bodies but not by bare eyes without a body. During orientation the presence of pike or catfish equipped with artificial eyes or a dummy with horizontal eyes elicited fin erecting display. This reaction was sporadic in the presence of a normal catfish which has very small eyes. The biological significance of this separate organization of exploration is discussed.

Ecological studies were carried out in the remaining habitat for medaka (Oryzias latipes), a marsh in the suburbs of Qinhuangdao City, Hebei Province, China. Sewage released from villages increases the nutrient levels in open water areas of the marsh, while in cattail (Typha angustifolia) and reed (Phragmites communis) beds the nutrient levels are decreased. There are fewer zooplanktons in the cattail and reed beds than in the open water areas. Sampling fishes with trap nets showed that medaka lived in dense populations in the cattail and reed beds, while the other three fish species, wild goldfish (Carassius auratus), topmouth gudgeon (Pseudorasbora parva), and mud loach (Misgurnus bipartitus), occupied the open water areas in the marsh. A little amount of paradise fish (Macropodus chinensis) was also found in the marsh. Japanese fresh-water shrimps (Macrobrachium nipponense) were found only in the influx canal from waterworks. Indoor aquarium experiments showed that the wild medaka in this marsh was easily cultured with commercial feed similar to domesticated strains. Some ecological aspects of the medaka were discussed based on the observations of the fish in the marsh.

On the Synonymy of Macropodus chinensis (Bloch, 1790) and M. opercularis (Linne, 1758) and the Rehabilitation of M. ocellatus Cantor, 1842 (Pisces, Belontiidae) The scientific name Macropodus chinensis (BLOCH, 1790) applied to the Roundtailed Paradisefish by MYERS (1932) is a junior synonym of Macropodus opercularis (LINNE, 1758), a related species with pronounced dark bars and a forked tail. This fact was clarified on the basis of the holotype of Chaetodon chinensis BLOCH, 1790 believed to be missing for a long time and now identified by the author. The correct scientific name for the Roundtailed Paradisefish should be Macropodus ocellatus CANTOR, 1842. The two type specimens of this taxon, stored in the British Museum (Natural History), are described and a lectotype is selected.

Macropodus opercularis is a popular ornamental fish and has been widely transported around the world. In this study, the complete mitochondrial genome of M. opercularis was reported. The circular genome is 16,496 bp in length and consists of 13 protein-coding genes, 22 tRNA genes, two ribosomal RNA genes, and one control region. The overall nucleotide composition was 30.9% A, 29.6% T, 24.7% C, and 14.8% G, with an A + T bias of 60.5%. The gene composition and the structural arrangement of the M. opercularis complete mtDNA were identical to most of the other vertebrates. The molecular data presented here could play a useful role in studying the evolutionary relationships and population genetics of Macropodusinae fish.

We examined the relationship between aggression and cerebral lateralization, as expressed by eye-use preference in a mirror-response paradigm, in six species of anabantoid fishes in the teleost family Belontiidae. Our objective was to test the hypothesis that frequency-dependent selection should decrease lateralization at the population level in more aggressive species. The mean laterality index did not differ significantly among the six species, nor did any of the species differ from zero, which suggests that populations of these fishes are neither left- nor right-eye biased. In spite of species differences in aggressive behavior, there was no relationship between population-level laterality and aggression as we had originally predicted. The degree of individual lateralization did differ significantly among some species. A phylogenetic generalized least squares (PGLS) analysis showed that these species differences were not due to phylogenetic distance. Individual laterality was also unrelated to aggression. Fishes in the genus Betta were the most individually lateralized, but varied in the intensity of aggressive behavior they displayed toward the mirrors. Taxa such as paradise fish (Macropodus opercularis and Pseudosphromenus dayi) were intermediate in eye-use preferences and gourami (Trichogaster trichopterus) displayed little cerebral lateralization. We also used the PGLS method to reconstruct ancestral values for individual lateralization in this group of fishes, from which we conclude that the ancestral condition was one of low variance in eye-use preference.

In this study, the complete mitochondrial genome of Macropodus opercularis was sequenced using Illumina-based de novo transcriptome technology and annotated using bioinformatic tools. The circular mitochondrial genome was 16,496 bp in length and contained two ribosomal RNAs, 13 protein-coding genes, 22 transfer RNA genes, and the control region. The gene composition and order were similar to suborder Anabantoidei. Phylogenetic analyses using concatenated amino acid and nucleotide sequences of the 13 protein-coding genes with two different methods (Neighbor-joining and Bayesian analysis) both highly supported the close relationship of M. opercularis to M. ocellatus , consistent with previous classifications based on morphological and molecular studies. Furthermore, family Channidae and Parachanna insignis were clustered in the same clade. Our results supported the inclusion of family Channidae in suborder Channoidei. The complete mitochondrial genome of M. opercularis will provide genetic markers for better understanding species identification, population genetics and phylogeographics of freshwater fishes.

The Siamese fighting fish (Betta splendens) is one of the popular aquarium fish. Serious attentions have been paid to the biodiversity of the fish. The mitochondrial genome of the Siamese fighting fish is reported to be 17 099 bp and includes 37 genes. The gene organization is similar to other fish mitogenomes. The control region is AT-rich and includes three tandem repeats. Phylogenetic analysis reveals that the fish is close to fish in the Macropodus genus. This mitogenome will assist in studying the mitochondrial variations and population structure in this fish and examine the evolutionary relationship among fish in the Osphronemidae family.

A series of laboratory experiments examined the effect of the size of predator models on the behaviour of larval paradise fish Macropodus opercularis L., of different age (15 and 20 days old). In a small runway, individually tested larval paradise fish could approach a model predator of different size, with or without eyespots. The duration of approach, the number of fleeings and backings were measured. Fifteen-day-old larvae showed similar moderate level avoidance to all models but fled more in the presence of larger models. The approach behaviour in 20-day-old larvae depended on the size of the model but only if it had eyespots, and larvae fled and backed more with increasing size of the model. However, manipulation of larval length within age category had no effect on predator avoidance. Since the recognition of the two eyespots seems to be age dependent, it is hypothesized that only larvae older than 20 days will behave in a ‘threat-sensitive’ manner in the presence of predator models by avoiding larger ones.

Several anabantoid species produce broadband sounds with high-pitched dominant frequencies (0.8-2.5 kHz), which contrast with generally low-frequency hearing abilities in (perciform) fishes. Utilizing a recently developed auditory brainstem response recording-technique, auditory sensitivities of the gouramis Trichopsis vittata, T. pumila, Colisa lalia, Macropodus opercularis and Trichogaster trichopterus were investigated and compared with the sound characteristics of the respective species. All five species exhibited enhanced sound-detecting abilities and perceived tone bursts up to 5 kHz, which qualifies this group as hearing specialists. All fishes possessed a high-frequency sensitivity maximum between 800 Hz and 1500 Hz. Lowest hearing thresholds were found in T. trichopterus (76 dB re I microPa at 800 Hz). Dominant frequencies of sounds correspond with the best hearing bandwidth in T. vittata (1-2 kHz) and C. lalia (0.8-1 kHz). In the smallest species, T. pumila, dominant frequencies of acoustic signals (1.5-2.5 kHz) do not match lowest thresholds, which were below 1.5 kHz. However, of all species studied, T. pumila had best hearing sensitivity at frequencies above 2 kHz. The association between high-pitched sounds and hearing may be caused by the suprabranchial airbreathing chamber, which, lying close to the hearing and sonic organs, enhances both sound perception and emission at its resonant frequency.

Dyadic encounters between paradise fish ( Macropodus opercularis L.) males were staged. In a first experiment, the duration of the dominance–submissive phase (cohabitation following the end of fighting) and the inter-encounter interval were manipulated. Measuring the duration both of threatening, fighting, mouthlock and head-tail display it was found that the memory of an aggressive encounter largely disappeared after 6 days and the duration of the dominance–submissive experience had no effect on the stability of memory formation in this species. In a second experiment, one group of fighting fish were separated just after the end of the fight, while concomitantly fish still fighting were also separated. On the next day, the aggressive behaviour of these two groups was compared and found that fighting decreased only in the group, of which the members had been able to finish the encounter. Our results show that: (1) post-contest harassment of the submissive has little if any impact on the behaviour changes that result; (2) an aggressive encounter affects the duration and patterns of a subsequent fight only if the fight is completed (i.e. dominance relationship develop); and (3) regardless, of the previous experience memory will fade after 6 days. In conclusion, the experience of winning or losing is the promoter of behavioural changes that result from aggressive experience. It is suggested that the social behaviour of the paradise fish determines the constraints of memory and learning in aggressive situations.

Agonistic encounters of all three species of the vocalizing genus Trichopsis were observed in order to compare species-specific fighting strategies and the specific investment in acoustics. Additionally, these encounters were compared to agonistic encounters of Macropodus opercularis which was considered to be mute. The aim of this comparison was to investigate if mute fishes stress visual or tactile displays. Within the genus Trichopsis, significant differences among the three species were found in qualitative and quantitative analysis of displays. Frontal display occurred only in Trichopsis vittata, whereas a strong tail-beating while vocalizing was only observed in Trichopsis pumila. Fight duration and the number of sounds and circlings were highest in Trichopsis schalleri. The largest relative distances between circling opponents occurred in T. pumila, the smallest species. Also, the number of attacks was lowest in T. pumila. Fighting assessment seemed to be different in each species. For the first time, sound production has been reported for Macropodus opercularis (infrequently and with extreme low sound pressure levels), but much more investment in visual and tactile displays has been demonstrated. Lowering the branchiostegal membrane and spreading the opercula occurred only in M. opercularis and was never observed in any of the Trichopsis species. The number of attacks was higher in Macropodus than in any Trichopsis species. The relative distance between Macropodus opponents while circling was closest compared to the three Trichopsis species. Visual and contact displays are reduced in extensively vocalizing fish species, like Trichopsis sp., compared to mute or seldom vocalizing species, like Macropodus. © 1996 Wiley-Liss, Inc.

Previous experiments on Betta splendens have shown that energy expenditures related to aggression are under social control. The present paper examines the biochemical energetics of social cohabitation in groups of Macropodus opercularis. The species is closely related to Betta splendens, however, dominants use somewhat different behavioral tactics against intruders. In contrast to Bettas, submissive Macropoduses are not harassed by dominants, but are confined to the bottom of the tank. This results in a reduced rate of oxygen consumption in defeated animals (Anabantid fish mainly use atmospheric oxygen). The only metabolic change, compared to isolated controls, is a reduction in hepatic glycogen content. Submissive animals have shifted carbohydrate metabolism towards anaerobic glycalysis. Substantial reductions in muscle proteins, lipids, and glycogen occurred in submissive Betta splendens. Thus, the sharp difference in behavioral strategy results in a sharp difference in the energetic consequences of aggression. A theory is presented regarding the possible role of energetic constraints in the control of behavior.

Paradise fish exhibit complex, environment-specific behavioral responses which consist of behavioral elements (motor and posture patterns) appearing in a typical, correlated manner. The genetic and environmental components underlying these phenotypical correlations have not been comprehensively investigated. Therefore, we have analyzed the behavioral elements of paradise fish from the nine populations of a 3 x 3 full diallel cross by employing a bivariate extension of the Hayman-Jinks variance-covariance analysis, demonstrating the presence of significant environmental and genetic correlations. To investigate the multivariate structure of the correlation matrices obtained, we subjected the phenotypical, environmental, additive genetic, and dominance correlations to principal-component analyses (PCAs). After rotation, the phenotypical principal factor pattern found was similar to previously obtained ones, suggesting stable underlying biological mechanisms. The environmental PCA extracted several environmental principal factors that were highly situation-specific. PCAs of the matrices of genetic correlations extracted only a small number of genetic principal factors which were not situation-specific, suggesting a relatively simple underlying genetic structure.

Critical Catalogue of the Types of the Fish Collection of the Zoological Museum Berlin. Part 6: Anabantoidei The sixth part of the type catalogue of the Agnatha and Fishes stored at the Zoological Museum of the Humboldt-University in Berlin includes the types of the suborder Anabantoidei. Some aspects about the types of this group are already published by the author (concerning Chaetodon chinensis BLOCH 1790, Trichogaster fasciatus BLOCH & SCHNEIDER 1801, Macropodus concolor AHL 1937), other are still at work (concerning Ctenopoma multispinis PETERS 1844, Ctenopoma nigropannosum REICHENOW 1875).