Different Duration of Memory for Conspecific and Heterospecific Fish in the Paradise Fish (Macropodus opercularis L.)

During an encounter with a conspecific male paradise fish memorize some features of their opponent. This is revealed by the shorter contest and significant changes in their behaviour at a second encounter with the same opponent. Memory of an opponent lasts for one day but is undetectable after a week. In contrast memorization of other species could easily be preserved for several months. A possible explanation of these different durations is discussed in relation to their functions in the life of the fish.     

The Ontogeny of Antipredator Behaviour in Paradise Fish Larvae (Macropodus opercularis): The Recognition of Eyespots

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 Role of Eyespots in Predator Recognition and Antipredatory Behaviour of the Paradise Fish,Macropodus opercularis L.

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 differential responses of the melanophores of the Paradise fish, Macropodus opercularis

Chromatic adaptation of the Paradise fish, Macropodus opercularis L., to illuminated backgrounds ranging from "white" to "black" shows that the pigment is most readily dispersed in the deepest-lying melanophores and least readily in the uppermost layers.     

叉尾斗鱼繁殖行为的观察

采用室内研究法对叉尾斗鱼(Macropodus opercularis)的繁殖行为进行了观察,结果表明,叉尾斗鱼分批产卵。雌雄鱼交配于21:35~21:55时开始,00:44~1:56时结束,整个过程持续约3~4 h,交配20~37次(Mean=28.83,n=6),时间跨度从8.9~18.6 s(11.31±2.61,n=141);只交配但雌鱼未产卵的伪交配4~6次(Mean=5.17,n=6),时间跨度从6.2~15.5 s(10.27±2.51 s,n=27);只完成交配第一步的伪交配36~117次(Mean=76.83,n=6),时间跨度1.4~15.0 s(5.69±2.31 s,n=440)。生殖期产卵8~9批,每批卵62~1 316粒(Mean=793.36,n=11);孵卵、护幼由雄性担当。卵从产出到孵化成鱼苗离开泡巢历时约4 d。野生叉尾斗鱼6~9月繁殖,产卵期水温22.4~33.5℃,溶解氧量1.1~4.2 mg/L,pH值6.0~7.0。     

Genotype-environment interaction in passive avoidance learning of the paradise fish (Macropodus opercularis)

Passive dark avoidance conditioning and effects of the presence and absence of a fish-like dummy on the training process were studied in four inbred strains of paradise fish. Strain differences were found in the shuttle activity during habituation trials, and in the sensitivity to the mild electric shock punishment. The presence or absence of the dummy in the punished dark side of the shuttle box had a genotype-dependent effect on the measures taken during the conditioning process. The statistical analysis of the learning curves revealed differences in the way the strains varied in the different environments, i.e. genotype--environment interaction components of variances were identified. The results are discussed in the light of previous investigations and their implication in further genetic analysis.     

The behaviour of the paradise fish (Macropodus opercularis) in two different open-fields. A correlation study

The behaviour of the paradise fish in a traditional "closed" and in a new "transparent" open-field was investigated. The traditional way of measuring ambulation scores was extended by recording ethologically defined behaviour units. The correlations found between the scores measured in the "closed" field and those measured in the "transparent" field are discussed in this paper.     

Prostaglandin-F2 alpha stimulates reproductive behavior of female paradise fish (Macropodus opercularis)

The function of prostaglandin-F2 alpha (PGF2 alpha) in reproductive behavior of adult female paradise fish (Macropodus opercularis) was evaluated. In experiment 1, females were allowed to spawn normally with a male and were left with that male until the following day when testing occurred. Subjects were then randomly assigned to one of three groups: PGF2 alpha (N = 8), vehicle control (N = 3), or a handling control (N = 3); for testing, females were removed, injected, then returned to the same tank. Seven of the eight subjects injected with 500 ng PGF2 alpha initiated complete reproductive behavior following injection. Vehicle and handling control subjects did not show any female reproductive behaviors. Prostaglandin-induced increases in sexual behaviors were seen from 15 to 75 min after the injection and were maximal approximately 45 min postinjection. In experiment 2, mature but unspawned (and presumably sexually naive) females were placed for 1 hr with males which were actively nestbuilding and parenting, following which subjects were either injected with PGF2 alpha (N = 6) or given a vehicle injection (N = 6). Experimental females did not behave differently from control females. Neither groups was observed to approach the male or initiate spawning behaviors following treatment; all subjects in both groups spawned on the following day. In experiment 3, sexually mature females were given extended familiarity with the male and the test tank. Pairs which had not spawned after 6 days (unspawned) were randomly assigned to experimental (N = 6) or control (N = 5) groups. Pairs which had spawned 1 day previously (N = 6) formed a "prespawned" comparison group. Females from the experimental and prespawned groups were injected with PGF2 alpha (500 ng), while the control females received a vehicle injection. Half of the "prespawned" females performed spawning acts while none of the unspawned or control females did so. Detailed behavioral analyses showed little or no effect of PG treatment, despite greater familiarity with the male. In experiment 4, females were placed with males and observed until the early signs of spawning, at which time they were injected with indomethacin (a PG synthesis inhibitor) or vehicle. The behavior of females treated with 35 micrograms (N = 3) or 70 micrograms (N = 6) of indomethacin was unaffected by indomethacin and largely indistinguishable from controls (N = 6). In summary, exogenous prostaglandins reinstate sexual behavior in female paradise fish. However, responsiveness to prostaglandins is influenced by prior sexual experience.(ABSTRACT TRUNCATED AT 400 WORDS)     

Artifical gynogenesis and mapping of gene-centromere distances in the paradise fish,Macropodus opercularis

Summary An efficient method has been developed for the production of gynogenetic paradise fish in order to obtain genetically homogeneous strains in a relatively short period. Diploidy of the gynogenetic embryos was restored by inhibition of the second meiotic division, and consecutive generations of normal, fully viable offspring were reared. Crossing-over frequencies and the relative positions of four marker loci were determined by analysing electrophoretic patterns of serum transferrin and esterases in the gynogenetic progeny of heterozygous females.     

Polymorphism and inheritance of serum esterases and beta-globulins in the paradise fish (Macropodus opercularis; Anabantidae)

Electrophoretic variants of serum esterases and beta-globulins in two subspecies of paradise fish (Macropodus opercularis) were studied. Four esterase loci (Est-1, Est-2, Est-3 and Est-4), a single transferrin (Tf) and another major beta-globulin locus (Bg) were identified by segregational analysis. Est-3 seems to be a monomorphic locus. Three alleles of Est-1, two of Est-2, two of Est-4, four of Tf and two alleles of Bg were found in the laboratory population. None of these loci were closely linked. Electrophoretic patterns of F1 hybrids confirmed the monomeric structures of each of the studied proteins. Allelic segregation at the Tf and Bg loci was normal in F2 and backcross populations. In crosses of the two Macropodus subspecies there were deviations from Mendelian ratios because of missing recombinant esterase phenotypes. Each of these would have been homozygous Est-2f/f. We suppose that Est-2f/f causes lethality in the early phase of development, except in the Est-1c/c, Est-2f/f combination characteristic of the parental subspecies M.o. concolor.     

Behavioural elements of the paradise fish (Macropodus opercularis). II. A functional analysis

The effects of various environmental influences, such as presence of a living predator, dominant conspecific or frightening artificial stimulus, on particular behavioural elements of the paradise fish (Macropodus opercularis) were studied. It has been found that certain sets of the elements are manifested as organizational complexes which characterize a certain mood or form of defensive behaviour. The compound elements of these complexes seemed to be partly interchangeable, partly under environmental control. The main behavioural complexes of the paradise fish were the Territorial complex characterizing the peaceful, home-living animal, Emotionality complex appearing in case of immediate and past danger, Active and Passive defense complexes which represent alternatives in defense, depending on particular stimulus settings. Some supporting evidence for these behavioural complexes are presented and discussed.     

Exploratory and fear behaviour in the Macropodus opercularis subspecies, M. o. opercularis and M. o. concolor

The exploratory and fear behaviours of the black paradise fish M. o. concolor, a subspecies of Macropodus opercularis, were studied and compared with those of an outbred and two inbred populations of M. o. opercularis. Adult females of both subspecies were used in the behaviour tests (open-field, novel-object approach, restricted space), and their behaviour in novel and startling situations was described by recording the sequence of ethologically defined units. It was found that M. o. concolor more often responded passively to novelty and fear-evoking stimuli. In 11 out of 14 test measures they were less active (p less than 0.01 and 0.001) than the outbred M. o. opercularis, but were very similar to our extremely timid strain P. Subtle differences of behaviour units were found between the subspecies, e.g. the absence of interrupted movements and unoriented panic behaviour in M. o. concolor. It is supposed that alternative passive and active strategies represent genetic polymorphism of defensive behaviour.     

Effect of the components of the physical environment on escape behaviour of the paradise fish (Macropodus opercularis)

Physical features of a seminatural environment on provoking various defence behaviour elements of the paradise fish were studied. It was found that most escape behaviour forms were under the control of visual stimuli. Transparent physical space induced escape and inhibited jumping. While the latter was induced by the presence of vertical untransparent surfaces. Dark places usually were avoided by the paradise fish. Placed into an unfamiliar environment in the presence of different escape routes the paradise fish seemed to make decisions after careful comparison of alternatives.     

Polymorphism and inheritance of serum esterases and β-globulins in the paradise fish (Macropodus opercularis; Anabantidae)

Electrophoretic variants of serum esterases and β-globulins in two subspecies of paradise fish ( Macropodus opercularis ) were studied. Four esterase loci ( Est-1, Est-2, Est-3 and Est-4 ), a single transferin ( Tf ) and another major β-globulin locus ( Bg ) were identified by segregational analysis. Est-3 seems to be a monomorphic. locus. Three alleles of Est-1 , two of Est-2 , two of Est-4 , four of Tf and two alleles of Bg were found in the laboratory population. None of these loci were closely linked. Electrophoretic patterns of F₁ hybrids confirmed the monomeric structures of each of the studied proteins. Allelic segregation at the Tf and Bg loci was normal in F₂ and backcross populations. In crosses of the two Macropodus subspecies there were deviations from Mendelian ratios because of missing recombinant esterase phenotypes. Each of these would have been homozygous Est-2^f/f . We suppose that Est-2^f/f causes lethality in the early phase of development, except in the Est-1^c/c, Est-2^f/f combination characteristic of the parental subspecies M.o. concolor .     

The influence of olfaction on exploratory behaviour in the paradise fish (Macropodus opercularis L.)

We studied the role of olfaction on the exploratory behaviour of the paradise fish. Intact animals showed habituation of exploratory behaviour toward a heterospecific fish after five consecutive encounters. Fish with olfactory nerves destroyed spent significantly longer time with exploration compared to the control even at the fifth encounter. We suggest that olfactory inputs have a strong influence on exploratory behaviour.