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• Pair-bonded convict cichlids express synchronized cortisol levels. • A stressor in the form of prolonged pair separation can effectively disrupt cortisol synchrony. • A disruption in cortisol synchrony does not lead to an immediate increase in intrapair aggression but may accompany pair-dissolution. Endocrine synchronization is a biological process often associated with social bonding. The mechanisms that mediate this process have been well studied in many vertebrate clades with evolved complex social behaviors. However, studies focusing on such processes in the less neurologically complex teleost clade are surprisingly lacking. In this study, we investigated the hypothesis that mated pairs of convict cichlids (Amatitlania nigrofasciata) perform cortisol synchronization and that the disruption of this might accompany pair-bond instability. Mated pairs were subjected to both behavioral and non-invasive waterborne hormonal assays to better understand the biological complexity of endocrine synchrony and its role in pair-bonding. Baseline cortisol assays indicated a positive correlation between male and female cortisol levels. Individuals that were subjected to a prolonged separation from their mate exhibited a negative correlation in cortisol synchrony after being reunited with their mate. Cortisol synchrony was disrupted, but pairs did not show a significant variance of intrapair aggression after initial pair reunion. However, more than half of the pairs that received the stressor exhibited significantly higher levels of intrapair aggression than their time matched controls approximately 1–7 days following this reunion, indicating pair-dissolution. Concurrently, pairs who underwent the stressor but maintained their bonds did not display an increase in intrapair aggression and also re-synchronized their cortisol levels. Not only does this study provide crucial insights in regard to the role of cortisol synchrony in serially monogamous systems, but it also suggests that the mechanisms that mediate the synchronization of endocrine through the formation of social bonds are more evolutionarily conserved than originally thought. [ABSTRACT FROM AUTHOR]

The enemy release hypothesis (ERH) posits that invasive species are released from their natural enemies in their invasive range, which promotes their successful invasion. In this study, we tested the ERH in a population of the convict cichlid Amatitlania nigrofasciata, an invasive species in Mexico. The ERH predicts that the convict cichlid: (a) is not infected by specialist helminth parasites in the invasive range; (b) has lower infection parameter values, as measured through richness, prevalence, abundance and diversity of helminths, than a native species—the redside cichlid Cichlasoma istlanum; and (c) is not affected in its condition factor by the abundance of helminths it carries. The convict cichlid was infected by two (33%) specialist helminths relative to the six specialist helminths that infect the cichlid in its native range. The convict cichlid had lower helminth richness and diversity than the redside cichlid. However, the prevalence and abundance of the parasite species varied between the host fish. While the prevalence and abundance of the nematode Rhabdochona kidderi was higher in the redside cichlid, the prevalence and abundance of the trematode Uvulifer sp. was higher in the convict cichlid. The condition factor in both host fish was not correlated with helminth abundance. Our results do not agree with the prediction that the convict cichlid is completely released from specialist parasites, nor with the prediction that this invasive species has lower infection parameter values than the native redside cichlid. However, our results agree with the prediction that the abundance of parasite helminths do not affect the cichlid's condition factor. More studies are necessary to determine the advantages that the convict cichlid could have in the invasive range when it is infected with a low richness and diversity of helminths. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate the effects of methanolic extract of nettle (Urtica dioica) on growth, reproduction, biochemical and immunological parameters of female convict cichlid (Amatitlania nigrofasciata). For this purpose, 54 fish were distributed in 3 treatments included: without supplementation (control), 0.1 g (NE0.1), and 0.5 g (NE0.5) nettle extract per kilogram feed over 56 days. The highest final weight (4.2 ± 0.1 g), weight gain (2.8 ± 0.1 g), and specific growth rate (2.0 ± 0.0% day−1) were recorded in NE0.1 group. Higher and lower feed conversion ratio were obtained in control and NE0.1 treatments, respectively. Hepatosomatic and viscerosomatic indices in NE0.1 treatment were significantly lower compared with control treatment. Fish fed NE0.1 showed significantly lower glucose (55.2 ± 6.5 mg g−1), cholesterol (28.4 ± 3.3 mg g−1), and triglyceride (211.5 ± 39.0 mg g−1) levels. Total protein (36.3 ± 3.4 mg g−1) and albumin (2.7 ± 0.1 mg g−1) showed a marked increase in NE0.1 treatment. Same trend was observed in C3, C4, and IgM concentrations. NE0.1 showed the highest number of eggs per female (183.7 ± 10.2), hatching rate (97 ± 0.7%), and larval survival rate at 3 days post hatch (86.3 ± 0.6%) compared with the other treatments. These findings indicated that 0.1 g methanolic extract of nettle kg feed−1 could enhance growth, improve metabolic, and immune function of convict cichlid. Moreover, this study confirmed that appropriate dose of nettle can positively promote reproductive performance which makes it as a valuable and cost-effective herb in aquaculture industry. [ABSTRACT FROM AUTHOR]

In this study, growth performance, body composition, digestive enzymes activity, mucosal and immunological parameters, cultivable bacterial populations, and stress resistance were investigated in juvenile convict cichlid fish (Amatitlania nigrofasciata) that received a dietary supplement containing 0 (control), 5 × 106 (LC1), 5 × 107 (LC2), and 5 × 108 CFU g−1 diet (LC3) Lacticaseibacillus casei PB-LC39. Two hundred and forty fish (2.44 ± 0.04 g) were assigned to twelve experimental aquariums and feed ad libitum three times a day for 8 weeks. After final sampling, final body weight, percentage of weight gain (WG %), specific growth rate (SGR), food conversion ratio (FCR), and protein content of whole‐body composition were significantly higher (P < 0.05) in fish fed LC1 diet than other treatments. Total protease, amylase, and lipase activities were also significantly higher (P < 0.05) in fish fed LC1 diet than other groups. Total protein from serum and mucus, lysozyme activity, total immunoglobulin (Ig), and serum globulin were significantly increased (P < 0.05) in fish fed LC1 diet compared with other groups. Moreover, total counts of lactic acid bacteria (LAB) in fish gut were significantly higher (P < 0.05) by different levels of L. casei PB-LC39 than the control group. Recovery rates of fish fed the probiotic cells, after an air-dive test, was significantly increased (P < 0.05) compared with the control group. Therefore, the results showed that L. casei PB-LC39 resulted in improving growth, health status, and stress resistance of fish during the rearing of juvenile convict cichlid fish. [ABSTRACT FROM AUTHOR]

Parental aggression can be a costly behaviour and flexible based upon context. While defence of offspring from potential predators has been well studied in the convict cichlid, it is unclear why parents are aggressive towards other parental pairs who are not likely to be offspring predators. In this experiment we explore the aggressive behaviour of pairs towards parental pairs and nonparental individuals using experimental presentations in the field. We found that parental pairs showed more aggressive displays towards other parental pairs than towards nonparental individuals. Bites did not differ between treatments, but there was a sex difference in bites, with males preferring to bite males and females showing no preference. As a higher level of display was observed both in the presence and absence of fry, we also examined the pair response to fry alone. Focal pairs were more aggressive to stimulus fry that were larger than their own fry, indicating that the larger stimulus fry represented a risk to the focal pair, as predicted by previous findings on brood mixing. We conclude that pair aggression towards parental pairs is a means to prevent brood mixing, and the greater aggression shown towards parental pairs suggests that the risk to parental pairs of brood mixing is greater than that of fry predation by nonparental fish. • We studied context-dependent decisions of biparental defence in convict cichlids. • Parents were more aggressive to other parental pairs than to nonparental adults. • Parents were also more aggressive to fry that were larger than their own. • Pair aggression towards parental pairs appears to be a means to prevent brood mixing. • Parents appear more threatened by brood mixing than by potential fry predation. [ABSTRACT FROM AUTHOR]

Early life experience may have lifelong influences on an individual's behaviour in ways that are either adaptive or maladaptive depending in part on whether these early experiences accurately foreshadowed conditions in later life. Stress coping style is one example of a suite of behaviours, or personality traits, that may be influenced by early exposure to stressful stimuli. Here we examine the effect of developmental stress exposure on behavioural syndromes in adult convict cichlids, Amatitlania nigrofasciata. We found that early life stress did not exert significant effects on personality traits in adulthood at the individual level, but that this stress exposure prevented the formation of an exploration–boldness syndrome that was present in the unstressed population. These results suggest that an exploration–boldness syndrome is present in this species in the absence of stress-related environmental constraints. However, greater plasticity may be selected for in response to early life cues that reflect high predator pressure. • Juvenile stress disrupted formation of an exploration–boldness behavioural syndrome. • Fish with prior stress exposure tended to display proactive coping behaviours. • Early stress exposure may result in higher baseline cortisol levels. • Early life constraints can cause lasting phenotypic change. • Natural constraints may lead to an exploration–boldness behavioural syndrome. [ABSTRACT FROM AUTHOR]

Habitat structure can impede visibility and movement, resulting in lower resource monopolization and aggression. Consequently, dominant individuals may prefer open habitats to maximize resource gain, or complex habitats to minimize predation risk. We explored the role of dominance on foraging, aggression and habitat choice using convict cichlids (Amatitlania nigrofasciata) in a two‐patch ideal free distribution experiment. Groups of six fish of four distinct sizes first competed for shrimp in one‐patch trials in both an open and complex habitat; half the groups experienced each habitat type first. Following these one‐patch trials, each group then chose between habitat types in a two‐patch trial while competing for food. Finally, each fish underwent an individual behavioural assessment using a battery of "personality" tests to determine if behaviour when alone accurately reflected behaviour within a social context. In the one‐patch trials, dominant fish showed similar food consumption between habitats, but chased more in the complex habitat. In the two‐patch choice trials, dominants preferred and defended the complex habitat, forming an ideal despotic distribution with more than half the fish and competitive weight in the open habitat. Within the groups, individual fish differed in foraging and chasing, with repeatabilities of 0.45 and 0.23 across all treatments. Although a higher foraging rate during the individual assessment predicted foraging rate and use of the complex habitat during the group trials, aggression and boldness tests were not reflective of group behaviour. Across groups, heavier dominants and those with higher foraging rate in the open habitat used the open habitat more, suggesting that both risk and energetic state affect habitat preference in dominant convict cichlids. [ABSTRACT FROM AUTHOR]

Positive differential allocation predicts that females will increase their parental investment when mated to high-quality males due to the benefits that these males provide to offspring. Differential allocation predicts trade-offs between current and future reproduction, but investment trade-offs can also occur within a breeding event for species that provide parental care. However, differential allocation studies that have examined investment in both gametic effort and parental care remain rare and have only been conducted in birds. Fish may have more conservative investment strategies due to the large effect that current reproductive investment has on future reproductive potential. We examined gametic effort and parental care in the convict cichlid, Amatitlania siquia , a biparental fish, in response to male size, a proxy for quality. We randomly mated females to either large or small males and measured fecundity and parental behaviour of both parents. Females mated to large males did not increase their fecundity, but did provide more parental care to offspring during the larval stage, which is when male desertion in natural populations is most likely. Male size did not predict the amount of paternal care provided to offspring during the larval stage. Female condition at the end of the breeding event was negatively associated with higher fecundity and level of maternal care provided. The observed pattern of maternal investment suggests that females limit costs to future reproduction by limiting their increased investment to only one component of their reproductive effort. The increase in maternal investment during the larval stage may also serve to stabilize the pair bond and ensure continued male care, which ultimately increases the reproductive success of both parents. These results highlight important taxonomic and parental care pattern differences and broaden our understanding of the factors that influence differential allocation in diverse taxa. Highlights • We examined maternal investment in response to mate quality in a biparental fish. • Female convict cichlids did not increase their fecundity for large males. • However, females provided more parental care to the offspring of large males. • Fecundity and maternal care were both negatively associated with female condition. • Increased maternal care may stabilize the pair bond and ensure male care. [ABSTRACT FROM AUTHOR]

(1) Predation selects for antipredator competence in prey. For fishes with parental care, brood predators exert selection on the morphological phenotype of offspring, and also exert strong selection pressure to promote parental care behavior of adults. (2) This review summarizes field and lab studies on the ontogeny of antipredator competence in convict cichlids, a freshwater fish with extended biparental care of their free-swimming young. (3) Here, data show that differences in swimming performance between small and large young are exploited by parents when they adopt (smaller) young. Velocity and acceleration of startle responses improves nonlinearly with body size, increasing rapidly at a point when the skeleton rapidly ossifies from cartilage to bone, at the size at which discrimination by adopting parents shifts, and the timing of change in the rate of change in area protected by parents. Convict cichlids in a Nicaraguan lake population showed a similar correlation among these traits, but these traits are delayed relative to Costa Rican fish. (4) Population divergence is likely explained by relatively more intense brood predation in the lake, which selects for different optima of larval antipredator competence and parental brood defense.

In many monogamous species, females behave aggressively toward other females, as they may threaten their exclusive access to paternal resources. However, in species with a high degree of breeding asynchrony not all females are true reproductive rivals. Female ornamentation that advertises sexual receptivity is a possible mechanism whereby parental females could assess the potential threat of rival females and attack only those which could challenge their mating status. Convict cichlids (Amatitlania siquia) are sexually dichromatic, monogamous fish that exhibit biparental care. Females develop gold ventral coloration when reproductively receptive and actively court males. We presented breeding pairs of convict cichlids with confined conspecific females to investigate whether parental response was affected by the intruder's reproductive status. We also investigated whether differences in partner quality within breeding pairs mediated the response to intruders, as mate quality influences both intra- and intersexual dynamics in many monogamous species. We found parental females responded more aggressively to reproductive intruders and that parental females mated to high quality males decreased the aggression they directed at general brood predators during the reproductive intruder presentation. Contrary to our predictions, we also found that males behaved aggressively toward reproductive intruders, particularly when paired with small females. Our results indicate that both parents engage in pair-bond defense and that differences in partner quality determine the level of aggression directed at extra-pair reproductive females. These findings suggest that when biparental care greatly increases offspring survival, reproductive success for both sexes may be maximized by cooperation and coordination, rather than conflict. [ABSTRACT FROM AUTHOR]

For species in which individuals spend at least some time in groups, dominance relationships and various social cues are often important for mate assessment and choice. For pair bonding species, social experiences may affect reproductive decisions in both sexes. We tested whether prior experience in a mixed-sex group and having a higher dominance status coincides with faster pair formation or spawning in a monogamous fish. Individuals having prior experience in mixed-sex groups paired with a novel fish more frequently than fish from same-sex groups. Fish in mixedsex groups performed more bites and lateral displays. Although spawning occurred infrequently across pairs, dominant fish from mixed-sex groups spawned more than dominant fish from samesex groups. Otherwise, there were no clear behavioural relationships between treatment group and subsequent pair formation or spawning, nor were behaviours of the paired fishes related to their prior treatment group. We do not know how mixed-sex social experience may have affected the physiology of those individuals, although our results support a reproductive priming effect. [ABSTRACT FROM AUTHOR]

Cerebral lateralization, the partitioning of functions into a certain hemisphere of the brain, is ubiquitous among vertebrates. Evidence suggests that the cognitive processing of a stimulus is performed with a specific hemisphere depending in part upon the emotional valence of the stimulus (i.e. whether it is appetitive or aversive). Recent work has implicated a predominance of right-hemisphere processing for aversive stimuli. In fish with laterally placed eyes, the preference to view an object with a specific eye has been used as a proxy for assessing cerebral lateralization. The habenula, one of the most well-known examples of an asymmetrical neural structure, has been linked to behavioural asymmetry in some fish species. Here, we exposed convict cichlid fish ( Amatitlania nigrofasciata) to both a social and non-social lateralization task and assessed behavioural lateralization in either the presence or absence of an aversive stimulus, damage-induced alarm cues. We also assessed whether behavioural asymmetry in these tests was related to asymmetry of the habenular nuclei. We found that when alarm cues were present, fish showed increased left-eye (and by proxy, right hemisphere) preference for stimulus viewing. In addition, females, but not males, showed stronger eye preferences when alarm cues were present. We did not find a relationship between behavioural lateralization and habenular lateralization. Our results conflict with previous reports of concordance between behavioural and habenular lateralization in this fish species. However, our results do provide support for the hypothesis of increased right-hemisphere use when an organism is exposed to aversive stimuli. [ABSTRACT FROM AUTHOR]

The convict cichlid (Amatitlania nigrofasciata) has been extensively examined in relation to many behavioral topics, such as courtship, pair-bonding, bi-parental care, and territoriality. Recently, this model species has been utilized in studies on genetics, endocrinology, and neuroanatomy, with an ultimate goal of connecting behavior with its underlying mechanisms. The goal of this study was two-fold: (1) profile the circulating levels of plasma 11KT in the male convict cichlid at multiple points during the reproductive cycle and (2) generally compare the hormonal profiles of the widely used laboratory populations and those of a free-living population in the streams of Costa Rica. The results of the field experiment showed that male convict cichlids had higher levels of circulating 11KT during courtship and lower during the parental care and non-breeding phases. The profile of the laboratory population was similar to the profile of the free-living individuals, with significantly higher levels of 11KT occurring during courtship than during parental care, though the level of 11KT during non-breeding phase was elevated in the laboratory. The high levels of 11KT during courtship and low levels of 11KT during parental care found in both the field and the laboratory is similar to what has been reported in other species of teleosts, and may suggest an important function of 11KT in the expression of courtship behavior and the subsequent onset of parental behaviors in this model species.

Amatitlania nigrofasciata is a small freshwater fish species native to Central America. Is a popular ornamental fish that has been traded and cultivated for the aquarium industry, introduced into temperate and tropical regions across the world. Two specimens of A. nigrofasciata were collected from two small creeks draining into the Guavio River, upper Meta River in Mambita, Ubalá, Cundinamarca, Colombia in the Piedmont Orinoco ecoregion. This is the first record of A. nigrofasciata in natural freshwaters of Colombia and the Orinoco River basin. Diagnostic characters of species and updated distribution at country level are provided. [ABSTRACT FROM AUTHOR]

Female convict cichlids ( Amatitlania siquia) exhibit bright orange ventral coloration that males lack. The behavioral implications of this color are poorly understood, particularly in naturally occurring populations where female coloration could play a role in the expression of territorial nest-guarding behaviors. In this field experiment, monogamous breeding pairs of convict cichlids were presented with 3D printed model conspecific intruders of three body sizes (small, medium, and large) exhibiting three orange patch sizes (large, small, or none) to observe how territorial aggression varied as a function of intruder size and female coloration. Individuals occupying breeding pairs that were defending hatched offspring were significantly more aggressive toward intruders with small and large amounts of orange than toward models lacking orange, indicating that color is an important context-dependent elicitor of aggression in this species. Males were significantly more aggressive toward the intruder than females, and male aggression was strongly influenced by their size relative to the intruder. When males were smaller than the intruder, they performed significantly more aggressive acts than when they were the same size or larger than the intruder; this trend persisted across three putative populations in Lake Xiloa, Nicaragua. A potential explanation for these findings is that the orange color functions as a signal of individual quality or breeding readiness and that breeding pairs increase aggression to repel intruders that pose the greatest threat to pair bond and nest maintenance. Significance statement: One or both sexes of many animal species possess brightly colored features that might communicate information about overall heath or reproductive status. In convict cichlid fish, males and females establish pair bonds and jointly defend their nest and offspring. Single females exhibit striking orange coloration that males and breeding females lack. Our field-based experiment provided evidence that more colorful females, which likely pose a threat to pair bond stability and nest maintenance, incite more aggression from breeding pairs than drab females. Our study suggests that color provides salient information about, perhaps, female quality or readiness to breed in natural populations, and adds to a growing body of research that seeks to understand the varied roles that colorful ornaments play in animal communication. [ABSTRACT FROM AUTHOR]

An 8-year-old female convict cichlid ( Amatitlania nigrofasciata ) was presented to the University of Wisconsin Veterinary Medical Teaching Hospital with a 2-month history of abnormal buoyancy; the fish spent most of its time in lateral recumbency on the aquarium substrate. During the initial visual examination of the patient in its transport aquarium, the fish was laterally recumbent on the bottom of the tank and had a mildly distended coelom. A transient response to empirical florfenicol therapy was reported, but the cichlid presented 1 month later in poor body condition and, again, in lateral recumbency. Owing to the poor prognosis, the fish was humanely euthanized and a necropsy was performed. The histopathologic results were consistent with a papillary carcinoma originating in the ovary, which invaded the caudal kidney and the swim bladder. The infiltration of the carcinoma into the swim bladder was suspected to be the primary cause of the clinically observed buoyancy abnormality. [ABSTRACT FROM AUTHOR]

In order to conserve and culture the cichlid fish Archocentrus nigrofasciatus, more information about its reproductive biology and its larval behavior and morphogenesis is necessary. Currently, temperatures ranging from 21 to 27 °C are used in ornamental aquaculture hatcheries. Lower temperatures are preferred to reduce the costs of water heating, and 23 °C is usually the selected temperature. However, there is limited information on culturing protocols for ornamental species and most of the information generated on this topic remains scarce. Thus, the present study examines the morphological development of Archocentrus nigrofasciatus during the yolk-sac period up to the age of 100 h post-hatching in relation to 2 temperature regimes used in ornamental aquaculture: a temperature of 27 °C (thermal optimum) and a decreased temperature of 23 °C (thermal tolerance). The results of this study suggest that the 27 °C temperature generates intense morphological changes in yolk-sac development in a shorter period. This has advantages as it reduces the time of yolk-sac larval development, and, thus, minimizes the transition phase to exogenous feeding and maximizes the efficiency at which yolk is converted into body tissues. The present paper provides necessary information to produce freshwater ornamental fish with better practices so as to increase larval survival and capitalize on time for growth. [ABSTRACT FROM AUTHOR]

How an organism deals with stressors is an integral component of survival. Recent research has shown that differences in a well-studied personality axis in fish, the shy–bold axis, relate to stress-coping behaviours. Bold fish tend to cope in a proactive manner (e.g. fighting) while shy fish cope more reactively (e.g. freezing). Because bold fish behave in a more risk-prone manner, it is likely that they encounter more stressors on average than shy fish. Greater exposure to stressful conditions may result in bold fish being less behaviourally sensitive to stressors (i.e. stress resilience). To investigate the idea of stress exposure leading to resilience, we examined whether fish personality (i.e. more bold or shy) affected anxiety-related behaviour in an open field task after fish had been exposed to a net-chasing stressor. We investigated open field behaviour in the presence and absence of a stressor (i.e. damage-induced alarm cues) to determine whether bolder fish would cope differently with a stressor than shy fish after recent stress exposure of a different type. Furthermore, we examined whether asymmetry in the habenula, an asymmetrical nucleus related to behavioural responses to stress and anxiety, is related to behaviour in the presence of stressors. We found no relationship between habenular asymmetry and behaviour in the open field. Net chasing increased activity in the open field for both sexes. We found an interaction between stress exposure and freezing behaviour in females but not in males. When females were not net-chased, shyer females showed a decrease in freezing behaviour when exposed to alarm cues, whereas bolder females showed no change in behaviour. When females were net-chased, there was no difference in freezing behaviour between bolder and shyer fish. We suggest that different parental care roles in this species lead to differential perceptions of the threat of stress between the sexes. [ABSTRACT FROM AUTHOR]

Defense of a territory is a primary factor determining the fitness of territorial individuals. Thus, territorial animals use a variety of means to lower the cost of territorial defense. Although landmarks are known to lower the defense costs of territories, little is known about how they could affect fundamental properties of territories, which could ultimately affect the demography, population regulation, individual behavior, and spatial ecology of a territorial species. This field study examined the effects of natural landmarks on territory size, shape, and defensive costs in Amatitlania siquia, a little-studied member of the convict cichlid group native to Costa Rica and Nicaragua. We investigated the territorial behavior of 103 breeding pairs in a caldera lake in Nicaragua. During 10-min focal observations, we recorded the locations at which residents chased intruders and then used these locations to outline the territory boundaries. Landmarks affected both size and shape of A. siquia territories. Territory size decreased as the percentage of the boundary at landmarks increased. Territories with <20% of their boundaries at landmarks were approximately circular in shape, while territories with 20-60% of their boundaries at landmarks were on average more elongated. These variations in territory size and shape significantly affected defense costs, with higher numbers of chases per square meter in small and elongated territories. These effects of landmarks on territory size and shape and defense costs are useful to understand the widely seen size and shape variations in naturally occurring territories. [ABSTRACT FROM AUTHOR]

Previous breeding experience affects parental care, yet in biparental species it is unclear how the inexperience of only one parent influences parental dynamics and division of labour. Using the biparental convict cichlid, Amatitlania siquia , I assessed how female breeding experience affects male and female parental behaviour. Females that either had bred (experienced) or were virgins (inexperienced) were paired with experienced males. Inexperienced females were less likely to form pairs and took longer to spawn. Female experience also affected parental division of labour between direct offspring care and territory defence. Female behaviour was compared in the presence and absence of their male partners. When males were present, all females divided their time similarly: more time was spent in direct care. When male mates were removed, experienced females divided their time equally between territory defence and direct care, while inexperienced females continued to spend more time in direct care. Males paired to inexperienced females divided their time equally between territory defence and direct care, while males paired to experienced females spent more time in defence. Males were also more aggressive towards experienced females. Overall, experienced females tended to adopt the male-typical role of defence, which probably caused the increased intrapair conflict in these pairs. This aggression helps explain why both experienced and inexperienced females showed similar role choices in the presence of their male partner and supports previous claims that male aggression helps maintain the division of labour in this species. Female inexperience potentially presents a trade-off for males: males paired to inexperienced females engaged in less intrapair conflict, but showed less division of labour between parental roles than is typical and were less likely to pair and spawn. The effect of female experience on division of labour, parental dynamics and pair bonding success probably influences other factors such as mate choice, effectiveness of parental care and overall fitness. [ABSTRACT FROM AUTHOR]

The signaling function of carotenoid-based orange ventral coloration expressed by female convict cichlids ( A. siquia) is still largely unknown. This field study examined the relationship between breeding female A. siquia orange coloration and predation stress, territorial competition, and offspring developmental stage. Female orange coloration decreased significantly with increased behavioral interactions with predators and heterospecific competitors, and the presence of wrigglers, fry, or juveniles was significantly associated with a lack of orange coloration. Multiple alternative explanations for these observations are discussed, including body carotenoid re-allocation and variation in environmental characteristics. [ABSTRACT FROM AUTHOR]

The convict cichlid, Amatitlania siquia, is a serially monogamous, bi-parental cichlid species native to Costa Rican rivers. Numerous field studies conducted in the Rio Cabuyo (Lomas Barbudal, Costa Rica) have provided a wealth of information regarding the behavioral ecology of this species. Recently a cichlid species that was previously not found in the Rio Cabuyo was identified as Hypsophrys nematopus. This influx of this non-native species provides an interesting ability to study the interactions of this potentially invasive species and to monitor the changes made by the native cichlid species. Over the course of several field seasons, I investigated the interactions between the native convict cichlid and the non-native cichlid. I surveyed the distribution of breeding pairs of both species and conducted behavioral tests to examine the interactions between the native and non-native species. I found an overall decline breeding pairs of both species over the course of the study. I found that both species were more aggressive to conspecific intruders and that female convict cichlids were aggressive to juveniles but males were not. These results provide important information concerning how native species interact with non-native species. It appears that the A. siquia population may experience a change in its reproductive behaviors due to the influx of H. nematopus. [ABSTRACT FROM AUTHOR]

Using probiotics can control pathogens by a variety of mechanisms. Probiotics can promote growth performance and have, therefore, become increasingly important in the aquaculture industry. Convict Cichlid belongs to the family of Cichlidae and is known for its rapid development in laboratory conditions and is suitable for behavioral examinations. The aim of this study was to evaluate the effects of Saccharomyces cerevisiae on growth performance, survival rate and body composition of Convict Cichlids (Amatitlania nigrofasciata). One hundred sixty eight Convict Cichlids (mean weight: 2.1 ± 0.12 g and mean length: 2.2 ± 0.05 cm) were fed by commercial diets with different concentrations of S. cerevisiae (0, 0.5%, 1%, 2%). At the end of the experiment, survival rate and growth indices were measured. Based on the results, growth performance significantly increased with probiotic, S. cerevisiae, specially, at the 2% probiotic level of concentration. In the present study, the best FCR (feed conversion rate), SGR (specific growth rate), CF (condition factor) and BWG (body weight gain) values were observed in a 2% concentration of S. cerevisiae. The results suggest that this yeast could improve feed utilization in this fish species. [ABSTRACT FROM AUTHOR]

Temperature and food availability are key drivers of growth and reproductive development in fishes, but information on how they interact is poorly understood. This study investigates the effects of water temperature and food availability on growth, sex ratio and gonadal development of the convict cichlid (Amatitlania nigrofasciata) which is an ornamental fish that may be a useful lab model. For this experiment, 180 juvenile convict cichlid (0.3 ± 0.02 g) were held at three different temperatures (26, 29 and 32 °C as T1, T2 and T3) and fed to satiation (S) or a restricted diet (R: half satiation) during a 56-day experimental period. Specific growth rate was significantly higher in T2S treatment than the other groups. The highest and lowest mean oocyte sizes were recorded in T1S and T3R groups, respectively. The sex ratio of fish held at 29 °C was male biased (female, 21.0%; male, 78.9%), but this was not seen at 26 °C (female, 47.6%; male, 52.4%) or 32 °C (female, 57.1%; male, 42.9%). In T1S and T1R treatments, oocytes developed more than the other treatments and in T2S group testicular development was more advanced than other groups. These results demonstrate the complex interplay of temperature and food availability on growth and reproductive development in the convict cichlid. Appropriate food availability significantly improves growth and reproductive processes, while restricted feeding decreases growth, survival rate and reproductive performance. • Effects of water temperature and food availability on growth and reproductive development of convict cichlid were examined. • Rearing convict cichlid at 26°C significantly promoted growth and ovarian development compared to higher temperatures. • Fish reared at 29°C had a male biased sex ratio whether fed to satiation or a restricted diet. • The fish at 32°C and restricted feeding rate had poor growth and reduced gonadal development. [ABSTRACT FROM AUTHOR]

Gonadotropin-releasing hormone (GnRH) neurons in the preoptic area (POA) of the hypothalamus play a key role in regulating reproductive function. These neurons in turn are modulated by environmental influences, including the social environment. In both the Old World cichlid Astatotilapia burtoni and the New World cichlid Amatitlania nigrofasciatus, the size of the soma of GnRH expressing neurons in the POA varies with social status in males and breeding state in females. Dominant males have larger GnRH-releasing cells than subordinate males, and spawning females have larger GnRH-releasing cells than brooding females. A. nigrofasciatus is monogamous and both sexes engage in similar levels of aggression and territorial defense. Here we test whether female A. nigrofasciatus display GnRH-releasing cell plasticity as a function of dominant status. We find that GnRH-releasing neuron soma sizes are larger in dominant females and that this difference is independent of differences in gonado-somatic index in A. nigrofasciatus. [ABSTRACT FROM AUTHOR]

Biparental care of young occurs when both parents provide some sort of care for offspring and can include a wide variety of behaviors, yet often studies focus on single aspects of parental care when trying to determine how each parent contributes. Here, we presented the biparental convict cichlid fish ( Amatitlania nigrofasciata) with two conflicting parental behaviors: retrieval of non-swimming offspring that have been displaced from the nest and defense against a conspecific intruder, a potential brood predator. We examined single males, single females, and pairs of parents to determine how males and females each contributed to overall parental care. Traditionally in this species, parents exhibit a division of labor (in which each parent contributes to all parental activities), but also exhibit a division of roles (in which males tend to favor the role of defense and females tend to favor more direct care, spending more time with offspring). We hypothesized that single parents would compensate for their absent mate, but that males and females would still favor preferred roles. Additionally, we hypothesized that there would be an asymmetrical expansion of roles, with females being more flexible. Our results show that the preferred roles of both parents were evident even when parents were without their mates and that males and females differed in their compensatory levels, at least when compared to the behaviors of the intact pair. Contrary to our prediction, females seem unable to fully compensate for the defensive behaviors usually exhibited by males, while males shifted completely to retrieve displaced offspring. [ABSTRACT FROM AUTHOR]