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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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

Megalocytivirus was detected from paradise fish Macropodus opercularis imported from Indonesia. Four of 11 fish (36%) in 2006 and 40 of 117 fish (34%) in 2008 were found to be PCR- positive for megalocytivirus. Phylogenetic analysis based on partial major capsid protein (MCP) gene nucleotide sequences revealed that the sequences detected in paradise fish were classified as Geno- type II, which includes freshwater fish isolates from Southeast Asian countries, closely related to infectious spleen and kidney necrosis virus (ISKNV), Murray cod iridovirus (MCIV), and dwarf gourami iridovirus (DGIV-2004). Paradise fish was added as a new host for megalocytivirus based on this study.

On the Phylogeny of the Species of the Genus Macropodus Lac. (Pisces, Belontiidae) In the present paper the genus Macropodus Lac. is defined as a monophyletic entity; the phylogenetic relationships among its three members Macropodus ocellatus, M. opercularis and M. concolor are discussed as well as the position of the Paradise fishes within the Belontiids.

The taxonomy of the paradisefishes of the genus Macropodus (F. Osphronemidae) has been confused due to inadequate sampling and the limitations of morphometrics and meristics in distinguishing species. The validity of the five currently described species, including two species described in 2002, was investigated using morphological characters. These characters included 25 morphometric measurements, otolith morphology, colouration, and counts of scales, vertebrae and spines in unpaired fins. Samples were collected from the described distributions of M. spechti Schreitmüller, 1936 and M. erythropterus Freyhof & Herder, 2002 in central Vietnam, and of M. hongkongensis Freyhof & Herder, 2002 in Hong Kong. Populations of M. hongkongensis were newly recorded in eastern Guangdong and Fujian Provinces, P.R. China. M. opercularis (Linnaeus, 1758) was also collected close to these locations and in the major intervening drainages. Macropodus ocellatus Cantor, 1842 was collected from Chongqing Municipality, China, and samples augmented by some museum specimens. The latter species could be distinguished from other species of the genus by both meristic and morphometric characters. The species M. spechti, M. erythropterus, M. hongkongensis and M. opercularis could not be reliably distinguished from each other by meristic and morphometric characters. Otolith morphology did not distinguish any species. Colouration discriminated all species except M. spechti / M. erythropterus. As a result, M. erythropterus Freyhof & Herder, 2002 was undiagnosable on the basis of morphology. The presence of M. hongkongensis in eastern Guangdong and Fujian Provinces, in addition to Hong Kong, indicates that distribution of this recently-described species clearly requires further investigation in south-eastern China.

In this paper, the quantitative post-embryonic development of the Asian freshwater fish nematode Camallanus cotti Fujita, 1927, is described. Larval and adult morphometrics were obtained by following the parasite's life cycle experimentally using copepods Macrocyclops albidus (Jurine) as intermediate host and guppies Poecilia reticulata (Peters), southern platyfish Xiphophorus maculatus (Gunther) and paradise fish Macropodus opercularis (L.) as definitive host. Additionally, adult worms were obtained from heavily infected paradise fish imported from Singapore. It is suggested that the gradual change in proportions of the worm's somatic body parts reflects the specific ecological role of each developmental stage. The free-living infective first- stage larva seems to be adapted for transmission, as indicated by its relatively long tail, designed to generate host-attracting movements, and its non-functional intestine. The second- and third-stage larvae from the copepod intermediate host seem mainly to invest in trophic functionality, i.e., the development of the buccal capsule and the oesophagus, which are crucial structures for the worm's successful establishment in the definitive fish host. Once in the fish intestine, the larvae enter a period of considerable growth. After the fourth (i.e., last) moult, a 72% increase in average female body length occurs. This is accompanied by doubling the average vulva-tail tip distance and the average tail length. The length of the female hind body expands in an accelerating allometric fashion, and seems to be closely linked to the posterior-wards expansion of the uterus. In the males however, growth seems to cease after the final moult. We conclude that female post-maturational body size, but especially the length of the hind body and the tail, are closely related to reproductive state, i.e., the developmental stage of the offspring in the uterus, and, probably, the worms' age. Any future taxonomical studies of camallanids in general, and C. cotti in particular, should thus be aware of the reproductive state of the females used.

Maximum Reactive Distance (RDmax) and the area of the Reactive Perceptual Field (RPF) for the fish Macropodus cupanus were determined, using the fourth instar mosquito larva (Culex fatigans) as the prey organism. RDmax and the area of RPF increased with increasing body weight of the fish as well as increasing food deprivation time. Satiation time (St) as a function of the weight of the fish and aquarium temperature were also determined. In larger W classes (570 and 270 mg) St was not influenced by temperature. To get satiated the smallest W class (80 mg) required feeding periods of 40, 30 and 20 minutes at 22 or 27, 32 and 37°C, respectively.

In this preliminary study defense behaviour patterns (fear responses) are described in two closely related, behaviourally different inbred labyrinth fish subspecies and in their F1 generation. The subspecies M. opercularis (characterized briefly by "active escape") and M. opercularis concolor (characterized by "passive escape") showed specific differences in the manifestation of certain defense behaviour patterns. In the F1 hybrid generation dominance and overdominance of M. opercularis was found in most defense behaviour patterns. Analysing the frequencies and sequences of movement patterns it could be shown that defensive behaviour is not a random or entirely "plastic" process but that there is sequential linkage between the patterns and they form characteristic clusters. Our results suggest that manifestations of different patterns are under genetic control and presumably, genetic determination of certain patterns is not very complex. Attempts were made to determine whole brain noradrenaline, serotonine and dopamine levels of the two subspecies and a significant difference was found in the noradrenaline content.

Fish 20–100 days of age were observed in brief conflicts with a stimulus fish of similar size and age. Four stages of behavior development were identified, based on quantitative changes in behavior which occurred with increasing age. Relatively little aggressive behavior occurs in the larval stage which includes fish up to about 40 days of age. Juveniles, age 40–70 days, approach, chase, and attack each other much more than do the larva. In the adolescent stage, 70–100 days of age, the incidence of species typical displays increases paralleling the onset of puberal changes in the testis and ovary. No sex differences in behavior were seen in fish up to 100 days of age. Among adult fish of unknown age males performed lateral threat displays more frequently than females as has been previously reported.

Bioassay studies reveal the toxicity levels of mosquito larvicides commonly used in the Trivandrum area (Kerala State, South India) to the indigenous larvivorous fishes Aplocheilus lineatus and Macropodus cupanus. The resistance of both fishes decreases with increasing time of exposure to the larvicides. When the two species are compared, M. cupanus appears to be more resistant than A. lineatus, probably because of its obligate air-breathing nature, and thus its tendency to absorb less toxicant from the aquatic medium across the gills. Thus M. cupanus is more suitable than A. lineatus for introduction into areas liable to be polluted by mosquito larvicides. The utilisation of A. lineatus in wells, in conjunction with the larvicide temephos, for anti-larval work is cautioned against, since the spray dosage of temephos against anopheline larvae in wells in India is in excess of the 48-h LC50 value of A. lineatus.

Socially isolated Macropodus opercularis showed a distinct approach response to water taken from the tank of a conspecific individual or a nonconspecific, Trichogaster trichopterus, but not to water from a tank without fish. It is proposed that these species produce chemical stimuli which are attractive to M. opercularis. Approach frequency and the total duration of approach during a 10-rain period of stimulation varied with the species and the sex of the stimulus fish but not with the sex of the subject. Subjects responded most frequently to the conspecific male and nonconspecific female stimuli and, least to the nonconspecific male stimuli. Rossi (1969) reported that solitary male Macropodus opercularis (family, Belontiidae; subfamily, Macropodinae) show increased nest building and aggressivity in response to female chemical stimuli. Observations in this laboratory during various experiments on social behavior (Davis, Harris, and Shelby, 1974) confirm that mature 34. opercularis respond to chemical cues from species mates. Water that has contained a female for a period of days can elicit immediate arousal consisting of erection of the medial fins and striking changes in skin color in an isolated male. These are elements of the species-typical responses which are seen in courtship and nest defense (Forselius, 1957; Ward, 1967). In addition, in a situation in which female stimulus water is" added slowly through a tube at the water surface, fish approach the incurrent tube and investigate the opening. The approach response occurs even when the behavioral arousal response does not, as when the stimulus is diluted with fresh water prior to entering the tank. 1We thank Jessie Shelby for her valuable technical assistance. 2Liem's classification of the order Anabantoidei into four families is preferred because it presents a more convincing hypothesis of the natural relationships between the divergent species in this group than does the older classification of Regan (1906).

The possible role of eyespot patterns in predator recognition by paradise fish was examined using a passive avoidance conditioning technique with various dummies or live goldfish. It was found that a low-intensity shock, although clearly uncomfortable, elicited exploratory behavior in the fish and that observable learning did not occur. However, if the paradise fish was shocked in the presence of a live goldfish or various fish dummies, exploration diminished and avoidance learning was detected. This was characterized by a considerable increase in latency to enter the shocked compartment. The most effective dummies were those with two laterally arranged eye-like spots. The possible role of species-specific key stimuli in avoidance learning and organizing defensive behavior of the paradise fish is discussed.

The habituation of exploration of a goldfish, Carassius auratus, by paradise fish, Macropodus opercularis, was examined. A first encounter of at least 1 min was necessary for habituation to be found in a second encounter 3 h later. When the paradise fish were allowed 5 min to explore the goldfish and the second encounters were staged between 3 h and 3 months later, persistent habituation was found. The relation between memories formed during encounters with other species and modelling of the environment by the paradise fish is discussed.

Siamese fighting fish (Betta splendens) were provided with 10 days of visual experience with other conspecifics or were visually isolated from them for 10 days. Bettas were then allowed to display aggressively toward the following stimuli: a conspecific, an alien species (Macropodus opercularis), and a mirror image. Differences between intraspecific and interspecific displays depended on the response measure used. Isolated bettas displayed more frequently to conspecifics than did the visually experienced bettas, and more so than any other group. Visually experienced bettas showed longer latencies to conspecifics than did isolated bettas. However, there were no differences in the other response measures (duration of display and time to absence of responding for 15 min) in any of the stimulus conditions. Whether there are differences between intraspecific aggression, interspecific aggression, and aggression toward a mirror image may depend on the response measures used and the procedures leading up to behavioral testing.

Pretrial intramuscular administration of the antigonadotropin, methallibure suppressed operant responding for conspecific visual stimulation. Four administrations of the drug during an 11 day period did not noticeably impair gametogenesis. Oral administration of methallibure for 5 weeks resulted in a decrease in frequency of lateral display, but not frontal display, in a 10 min trial with a live stimulus male, and a decrease in the gonadosomatic index and fertility but not spawning readiness. The possibility that methallibure disrupts catecholamine synthesis is discussed.

The behavioural effects of morphine on random bred Macropodus opercularis , five strains of this species of fish, and the closely related subspecies M. opercularis concolor , were assessed by an ethopharmacological analysis based on the study of different active and passive behavioural units. The results showed that morphine 1. 1) exerted qualitatively different effects in the different strains, 2. 2) did not involve a general enhancement of active behavioural units or a general behavioural depression, but a selective increase of some of them, or the outcome of stereotyped behaviour. In general these findings stress out the importance of ethopharmacological studies for assessing qualitative behavioural differences which may be related to genetically-modulated neurobiological differences.

Investigations of the effect of certain environmental factors on predatory efficiency of the indigenous larvivorous fishMacropodus cupanus indicates the dependence, in a quantifiable way, of predation on the environmental complex surrounding the prey-predator system. Prey consumption is less at low temperatures and increases significantly with rise in temperature. Feeding under conditions of light is significantly higher than in darkness. Salinities of up to 21.83‰ do not affect predation rate, except that owing to stress conditions, prey intake at 21.83‰ is lower than at 0.12‰ Considering fish size, in terms of unit body weight, predation declines significantly as size increases. However, when total body weight is considered, predation increases with increase in fish size. Environmental factors do not alter the time course of predation regularly or significantly, perhaps owing to haphazard intake subsequent to satiation and/or a ‘learning’ factor. The higher predation rate of this fish when compared to the conventional larvivoreGambusia affinis indicates its potential as a biocontrol agent of mosquito larvae.

Passive dark avoidance conditioning was studied in four inbred strains of paradise fish in the presence and absence of a fish-like dummy during the training process. Strain differences were found in exploratory activity during habituation trials and also in the sensitivity to the mild electric shock punishment. The impact of the fish-like dummy also depended on the genotype.

Paradise fish, macropodus opercularis, were given inescapable shocks in the black side of a two-compartment box. Following training they showed acquisition of a target-striking instrumental response which permitted them to escape from the black compartment to a white compartment. Non-shocked control Ss also showed evidence of learning, probably based on an exploratory drive, but their behavior was far less persistent than that of the experimental group. The results are compared with those of other studies, on both the fish and mammals, which have investigated the effects of conditioned fear training, and some theoretical implications are drawn.

Transversotrema chackai sp. nov. adult of Cercaria chackai, is described. They are found as adults beneath the scales of three species of fishes, Macropodus cupanus (CUV & VAL), M. cupanus var. Dayi (DAY) and Barbus puntius (HAM & BUCH). This species is compared with other known adults of the genus Transversotrema and the creation of a new species is justified.

1. In the paradise fish, Macropodus opercularis, the dark-colored or normal type is a Mendelian dominant to the albino.2. A description is given of the cell groupings which form the basis of the color pattern.3. The melanophores are entirely absent from the albino but all other types of chromatophores are present.

Betta splendens (Siamese fighting fish) were given 10 days of visual preexposure to either Macropodus opercularis (paradise fish) or their own mirror images. Separate groups of bettas were then allowed to display aggressively toward one of the following stimuli: a conspecific, an alien species (Macropodus opercularis), or a mirror image. Bettas displayed more frequently, and for a longer duration, when tested with either another betta or their own image than when tested with a macropodus. Bettas required more time to reach a criterion of no displays when tested with their own mirror image than when tested with the macropodus fish; this measure did not differ between the betta test condition and the macropodus test condition. Strength of aggressive displays in bettas is dependent of previous exposure conditions (Miley & Burack, 1977), the particular stimuli used in behavioral testing, and measures used in recording the aggressive response.

Informal observations had suggested that low-level nocturnal illumination was necessary for egg survival following normal spawning of Macropodus opercularis. To confirm those observations, spawned pairs of M. opercularis were left overnight with their eggs, with either low-level illumination (n = 21) or in complete darkness (n = 23). In complete darkness 17 of 23 pairs showed complete egg loss the following morning, while none of the low-level illumination group showed evidence of egg loss. Possible explanations of this phenomenon are discussed.

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

In 1937, Noble and Kumpf reported briefly that in juvenile female fighting fish (Betta splendens), spaying may induce the regeneration of testicular tissue and the development of male secondary sex characters in some individuals which have undergone this operation. In 1951, Kaiser and Schmidt obtained corresponding results after simular experimental intervention. Although occasional occurrence of various forms of intersexuality is well known from teleosts (Atz, 1964) and spontaneous sex inversion as well as simultaneous hermaphroditism does occur among bony fish (Atz, 1964; Reinboth, 1970), those phenomena in Betta are quite unusual. Since the forementioned papers by Noble and Kumpf (1937) and Kaiser and Schmidt (1951) do not provide sufficient technical data, we started to repeat and extend those studies, in order to learn more about the mechanisms that might be involved in this strange process. Since the results of a thesis by Becker (1969) and a further study by Eckert-Roland (1969) on the same topic have not been published, the following report summarizes the essential data that we obtained.

Macropodus opercularis were reared in isolation, with conspecifics, or cross-reared with nonconspecifics. As young adults, cross-reared subjects presented with live conspecific and mirror image stimuli performed social displays less frequently than controls, while isolates did not differ from controls. In a spawning trial, no differences were found between groups. These results suggest that experience with an alien species may reduce the readiness to perform species-specific social displays. Investigations of imprinting and attachment behavior indicate that social stimulation is necessary for the ontogeny of species-typical social behavior in mammals (Cairns, 1972) and in birds (Bateson, 1966, 1971). Juvenile mice, sheep, and dogs which have previously been kept with members of an alien species may show attachment behavior toward the nonconspecific (Denenberg, Hudgens, and Zarrow, 1964; Nagy, 1965; Cairns and Johnson, 1965; Cairns and Werboff, 1967; Fox, 1969). The effect of cross-species rearing on adults social behavior has apparently not been extensively investigated. As adults, Mus reared with Baiomys show a social preference for Baimoys, though the Mus freely mate with conspecifics (Quadagno and Banks, 1970). Lagerspetz and Heino (1970) found that mice cross-reared with rats preferred rats in a social preference test as adults, and showed reduced sexual behavior toward mice. Adult male guinea pigs which are reared with chickens or rats court conspecifics and the cross-reared species as well (Beauchamp and Hess, 1971, 1973). Social isolation beginning early in development has marked effects on adult behavior. Rats isolated as early as 14 days show normal sexual behavior (Beach, 1958), although neonatal isolation disrupts adult mating behavior (Gruendel and Arnold, 1969). Isolated male guinea pigs, cats, and dogs exhibit poorly organized sexual behavior patterns (Valenstein, Riss, and Young, 1955; Rosenblatt, 1965; Beach, 1968; Coulon, 1971) and isolation-reared rhesus monkeys show profound disruption of adult social behavior (Harlow and Harlow, 1966). In some birds the development of a juvenile social attachment 343

The aggressivity of adult males and females was evaluated by measuring (1) the frequency of aggressive displays that individuals made toward a mirror image stimulus following varying periods of social isolation, (2) the display frequency in brief, unisexual and bisexual bouts with live opponents, and (3) the reinforcing effects of mirror image stimulation on performance of an approach response. Isolation up to seven days increased aggressivity in both sexes. Males performed lateral display toward a mirror image or a live conspecific more frequently than females. Mirror image stimulation also was a stronger positive reinforcer in males than in females.

The behavioural effects of morphine on fish (Macropodus opercularis) were studied by an ethopharmacological analysis. For this purpose active and passive behavioural units were observed. The results show that morphine treatment had a stimulating effect. However, the treatment resulted not in a general enhancement of active behavioural units, but in a selective increase of some of them, such as swimming and erratic behaviour, or in stereotyped behaviours, such as circling. By contrast, high dosages of morphine resulted in a decrease of escape and of standing under the surface behaviours.

Responses of male paradise fish (Macropodus opercularis) habituated to repeated presentations of mirrors or live conspecifics. Continuous exposure resulted in less rapid habituation than repeated, briefer exposures over days. A live conspecific initially evoked more aggressive responses, but fish spent the same time close to a mirror or a conspecific. Subsequent recovery of responses followed a progressive course during visual isolation. Biting was potentiated by habituation and subsequent recovery. The necessity of using multiple measures of behavior, and some possible motivational basis for the behavior are discussed.

Approach behaviors toward conspecific chemical stimuli of the opposite sex were examined in five Belontiidae species: Betta splendens, Macropodus opercularis, Colisa labiosa, C. lalia, and Trichogaster trichopterus. Approach was measured by (a) preference for section 1 of a three-section tank, which contained a vertical tube that introduced the stimulus water, and (b) occupancy of the tube. Experiments 1A and 1B showed that (a) approach behaviors were displayed by the isolated male Betta only to ripe-female stimulus water, (b) group-housed males of the remaining four species were not attracted to female-conditioned water, and (c) socially isolated males of these four species preferred section 1 during presentation of either ripe- or nonripe-female-inhabited water but occupied the tube only during exposure to ripe-female-conditioned water. The findings of Experiment 2A were that (a) the female Betta, regarless of physiological state, showed approach behaviors to male-inhabited water and (b) only ripe females of the remaining species indicated a preference for section 1 during male-water exposure but performed no tube entries. Results of Experiment 2B indicated that social isolation of the females, especially ripe females, facilitated their approach behaviors.

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.

The tendency for predatory responses to habituate and to be reinstated through sensitization and the passing of time was studied in two species of fish (the goldfish and the paradise fish). Prey (live brine shrimp), confined in a clear plastic tube were presented for short daily exposures to individual fish. Bites directed at the stimulus tube containing the prey were the primary response measure. In both species biting decreased significantly over the 6 days of the experiment. Reinstatement of the habituated response occurred by two means: (1) reinforcement (i.e. allowing the fish to chase and consume the prey), and (2) passing of time (10 days) with no intervening stimulation (recovery). Reinstatement could not be produced by presenting a novel stimulus, nutritive stimuli, nor by a shorter recovery interval.

THE number of vertebrae in fish is considered to vary with temperature during early development. From field observations, it is generally considered that fish subjected to low temperature tend to have more vertebrae than those in warmer waters. This was supported by the experiments of Gabriel1 on Fundulus heteroclitus, of Dannevig2 on Pleuronectes platessa, and of Kubo and Kobayashi3 on Oncorhynchus keta. On the other hand, Taning4 showed that the lowest average number of vertebrae was obtained at an intermediate temperature, while both higher and lower temperatures produced a higher average in his experiment on Salmo trutta trutta. A similar result was obtained by Lindsey's5 experiments on Macropodus opercularis. Thus the results of experimental studies are not consistent.