Juvenile stress disrupts the development of an exploration–boldness behavioural syndrome in convict cichlid fish

The convict cichlid fish, Cichlasoma nigrofasciatum, exhibits extended parental care in both the laboratory and the field. Families of this species were observed in Lake Xiloa', Nicaragua, during part of the breeding season. Young fry (less than 5 days free swimming) could be induced to follow a variety of "dummy" parents when their own parents were restrained at a distance. Older fry fled the dummies in the same manner as they fled predators. Two laboratory experiments were conducted to analyze further the responses of convict cichlid fry to parental dummies. Experiment I demonstrated the following: 1. Fry showed consistent preferences in tests with 5 pairs of mechanically moved dummies. Some of these preferences involve species characteristic cues. 2. Responsiveness to dummies increased over time within a test and over repeated tests. Responsiveness changed non-monotonically with age; those tested at 1 to 3 days free swimming were most responsive, 6 to 8 day old fry were least responsive and 14 to 16 day old fry showed intermediate responsiveness. 3. Preferences were weaker in the older, less responsive fry but were generally in the same direction as in younger fry. Experiment II tested the effects of experience with a particular dummy on the preferences demonstrated in Experiment I. For all ages and for most dummy pairs there was a significant interaction between training condition (preferred vs non-preferred dummy) and preference. Experience with a single dummy also resulted in a general increase in responsiveness to the two dummies in the preference test. The present results are discussed in terms of selection pressures presumed to operate on natural populations of C. nigrofasciatum and also in terms of research on "imprinting" in precocial birds.

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Manipulating territory size via vegetation structure: optimal size of area guarded by the convict cichlid (Pisces, Cichlidae)

Canadian Journal of Zoology ◽

10.1139/z02-002 ◽

2002 ◽

Vol 80 (2) ◽

pp. 376-380 ◽

Cited By ~ 14

Author(s):

Cindy Breau ◽

James WA Grant

Keyword(s):

Growth Rates ◽

Vegetation Structure ◽

Cichlid Fish ◽

Territory Size ◽

Optimal Size ◽

Convict Cichlid ◽

Food Patch ◽

Costs And Benefits ◽

Archocentrus Nigrofasciatus ◽

Data Support

To test the predictions of optimal territory size models, we attempted to manipulate the size of area that a dominant convict cichlid fish (Archocentrus nigrofasciatus) would defend around a food patch by placing simulated vegetation at three different distances from the edge of the patch (0, 11, and 22 cm). As expected, the size of area defended against four smaller intruders increased as the vegetation was moved farther from the patch. Consistent with optimal territory size models, both the costs of defence, measured as chase radius and chase rate, and the benefits of defence, measured as the amount of food eaten by the defender, increased with the distance of the vegetation from the patch. Growth rates of the defenders, however, did not differ among the treatments, perhaps because the benefits of monopolizing food were balanced by the costs of defending a larger area. Our data support the hypothesis that the size of a guarded area around an ephemeral resource patch affects both the costs and benefits of defence.

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Effects of Parent and Offspring Food Rations On Parental Care in the Convict Cichlid Fish (Pisces, Cichlidae)

Behaviour ◽

10.1163/156853994x00352 ◽

1994 ◽

Vol 129 (1-2) ◽

pp. 63-77 ◽

Cited By ~ 5

Author(s):

James D. Kieffer ◽

Robert J. Lavery

Keyword(s):

Parental Care ◽

Environmental Conditions ◽

Food Supply ◽

Cichlid Fish ◽

Food Abundance ◽

Convict Cichlid ◽

Cichlasoma Nigrofasciatum ◽

Convict Cichlids ◽

More Care

AbstractAnimals may provide more care for their young under certain environmental conditions. For instance, if food is plentiful parents may invest more in the current brood than if food is scarce, assuming that food abundance is correlated with parent and offspring condition. In this experiment, we manipulated food levels (low vs high) for both parents and offspring to determine if parental care is influenced by parental and/or offspring condition in the convict cichlid, Cichlasoma nigrofasciatum. Parents which were fed a higher ration gained weight, whereas parents fed a lower ration lost weight. Similarly, young which were fed a higher ration were significantly larger than young fed a lower ration. Parents which were fed a higher ration defended their brood more vigorously than parents fed a lower ration. Offspring condition had little effect on parental care. Furthermore, females consistently invested more than males. The results show that parental convict cichlids adjust care in response to their own food supply rather than that of their offspring.

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