Convict Cichlids Research Articles

Maintenance of Spatial Distribution by Convict Cichlid Pairs Is Influenced by Parental Defense Behavior toward Conspecific and Heterospecific Parental Pairs

Maintenance of Spatial Distribution by Convict Cichlid Pairs Is Influenced by Parental Defense Behavior toward Conspecific and Heterospecific Parental Pairs

Aggressiveness overcomes body‐size effects in contests between native and invasive cichlid fishes

AbstractIn animal fights, there are often size asymmetries between opponents. Although larger individuals typically dominate smaller ones, size is not the sole determining factor, as the competitors' motivation, aggressiveness, resource value, physiological characteristics, and strength also play crucial roles in fighting outcomes. In this study, we evaluated the influence of body size on dominance hierarchy and contest success during intra‐ and inter‐specific contests in two fish species: the native mojarra of the Balsas basin Amphilophus istlanus and the invasive convict cichlid Amatitlania nigrofasciata. We used size‐asymmetric males to carry out experimental contests. The number and type of aggressive behaviors, time to contest outcome, and dominant individual at the end of the contest were determined. In contests between two native mojarra, the smaller individual always lost. In contests between convict cichlids, the smaller contestants lost in all contests where size asymmetry was greater than 20%. In interspecific contests, the native mojarra performed more aggressive behaviors than the invasive convict cichlid and dominated convict cichlids despite a size disadvantage. This suggests that in terms of competition via interference, the native mojarra can counter the arrival of the invasive convict cichlid.

Effect of water calcium, copper, and silver on branchial Na+ permeability in a characid and cichlid fish

We tested the hypothesis that water Ca2+ is involved in control of branchial Na+ permeability in low pH tolerant convict cichlids and black neon tetras. We measured Na+ efflux in water with different Ca2+ concentrations during exposure to low pH, silver, and copper, at levels which are known to stimulate Na+ efflux. For convict cichlids at pH 7.5 exposure to 0 μmol L−1 Ca2+caused Na+ efflux to rise 2.5 times above controls at 100 μmol L−1 Ca2+. However, raising [Ca2+] to 500 μmol L−1 had no effect. Upon exposure to pH 3.5 (control [Ca2+]) Na+ efflux rose almost 5× and increasing the [Ca2+] 5-fold did not reduce the magnitude of stimulation. Exposure to 1 μmol L−1 silver and 25 μmol L−1 copper stimulated Na+ efflux 7×, and 2×, respectively. Raising [Ca2+] concentration during metal exposure halved the stimulation of Na+ efflux caused by silver, and eliminated the stimulation elicited by copper. For black neon tetras raising or lowering water [Ca2+] had no effect on Na+ efflux at pH 7.5. Exposure to pH 3.5 caused Na+ efflux to rise 2.5× but changing [Ca2+] had no effect. Exposure to 1 μmol L−1 silver, or 25 μmol L−1 copper caused Na+ efflux of tetras to rise 4-fold and 3-fold, respectively. Raising [Ca2+] during silver exposure reduced the stimulation of Na+ efflux by about 50%, but during copper exposure increased [Ca2+] had no effect on stimulation of Na+ efflux. These results suggest water Ca2+ plays a role in control of branchial Na+ permeability in cichlids, but perhaps not tetras. In addition, the silver and copper concentrations required to inhibit Na+ uptake and stimulate Na+ efflux were higher than the concentrations used on non-characids and non-cichlids, which indicates that our fish are much more tolerant of these metals.

HABITUS COMPARASION, GROWTH PATTERN AND CONDITION OF CONVICT CICHLID (Amatitlania nigrofasciata GUNTHER, 1986) IN THREE LAKES ECOSYSTEMS IN BALI

Convict cichlid (Amatitlania nigrofasciata) belonging to the Cichilidae family has inhabited in Tamblingan Lake, Buyan Lake and Beratan Lake. The existence of this fish species is suspected due to accidental introduction activities. The aims of this study ware to reveal differences in habitus, growth patterns and conditions of convict cichlid in the three lakes on the island of Bali. Samples of convict cichlid were taken by bubu traps, that placed in the littoral zone of the lake. 19 morphometric characters were measured using a digital caliper, then each fish sample was weighed. The growth pattern and condition of convict cichlid are known by using the equation of the length-weight relationship and the condition factor. There were 888 individuals of convict cichlid caught during this study, consisted of 385 fish from Tamblingan Lake, 371 fish from Buyan Lake, and 132 fish from Beratan Lake. Moreover, 108 fish consisting of 36 fish from each lake were further analyzed by measuring 17 additional morphometric characters. The results of measuring the morphometric characters of the observed convict cichlid had different variations for the characters of head length and predorsal length. There was diversity for several morphometric characters of the convict cichlid in Buyan Lake which are a collaboration of characters between the convict cichlid in Tamblingan Lake and in Beratan Lake, namely on the basic characteristics of the anal fin, dorsal fin base, body length, postorbital length, and tail height. The growth pattern of this species in the three lakes was negative allometric and the condition of this fish species was in good condition with the average value of condition factor ranging from 0.95–1.05.

Lead has different impacts on behavior of the native Mexican mojarra and invasive convict cichlid

Lead has different impacts on behavior of the native Mexican mojarra and invasive convict cichlid

Thyroid hormones in development of coloration of two species of Neotropical cichlids.

Neotropical cichlids demonstrate an enormous diversity of pigment patterns, a morphological trait that plays an important role in the adaptation and speciation. It has been suggested that alterations of the activity of the thyroid axis, one of the main endocrine axes regulating fish ontogeny, are involved in the development and diversification of pigment patterns in the Neotropical cichlids. To test this hypothesis, we assessed the thyroid hormone developmental dynamics and pigment patterning, and experimentally induced hyper- and hypothyroidism at different developmental stages in convict cichlid, Amatitlania nigrofasciata, and blue-eye cichlid, Cryptoheros spilurus. We revealed that both species display a similar type of coloration development and similar reactions on changes of the thyroid hormone level, but species-specific differences in hormonal dynamics and thyroid hormone-responsiveness. These findings indicate that thyroid hormone is a necessary but not sufficient signal to induce the transition from larval to juvenile coloration, and is a component of a complex, concerted endocrine cascade that drives skin development.

Invasive cichlids (Teleostei: Cichliformes) in the Amacuzac River, Mexico: Implications for the behavioral ecology of the native Mexican mojarra Amphilophus istlanus

The introduction of species is a leading cause of biodiversity loss and habitat alteration. Several species have invaded Mexican freshwater ecosystems, adversely affecting native fishes. Specifically, in the Amacuzac River of the Balsas Basin (Central Mexico), at least four non-native cichlids have been recorded: tilapia Oreochromis sp., convict cichlid Amatitlania nigrofasciata, spotcheek cichlid Thorichthys maculipinnis, and green terror Andinoacara rivulatus. These species co-occur with the Mexican mojarra Amphilophus istlanus, the only native cichlid in the Basin. Invasive cichlids compete for resources such as shelter and food, and prey on offspring of the Mexican mojarra. In the presence of invasive cichlids, the costs and risks of foraging and finding available shelter increase for the native cichlid. Predation pressure from invasive cichlid fishes on the Mexican mojarra increases the time invested by parents in caring for offspring and their stress levels, potentially contributing to Mexican mojarra population declines. Here, we gathered the best evidence available to discuss some mechanisms and consequences of such co-occurrences in relation to reproductive behaviors, parental care, competition for resources, and dominance hierarchy, and how the four invasive cichlids have negatively affected the Mexican mojarra.

INDEKS STRUKTUR KOMUNITAS DAN SAPROBITAS PLANKTON SERTA CHECKLIST KEBERADAAN NEKTON DI PERAIRAN DANAU BERATAN, BALI

Beratan Lake was mainly popular for tourism and aquaculture activities that affecting water's environmental characteristics. The water healthiness indicator can be seen through the organism's existence, namely plankton to nekton biota that can be uses as an essential parameter in monitoring water conditions. This study aims to determine the plankton community structure index, saprobity index and the presence of nektons in the Beratan Lake. Plankton were sampled using the pouring method while the nekton sample was taken randomly through direct sampling with fishing nets and conducted interviews with the surrounding local community and fishermen. The results of the study found that the abundance of phytoplankton was dominated by Staurastrum with abundance level 1,836.92 ind/L. Meanwhile, the zooplankton was dominated by Rotifera with abundance level 8.17 ind/L. The diversity index, uniformity and dominance of phytoplankton are 1.31, 0.60 and 0.33 respectively, while the saprobity index is 1.08 which classifies the waters of Beratan Lake as being in a lightly polluted condition. There were 18 species of nektons in Beratan Lake were found, with one endemic species Rasbora balinensis and 13 foreign fish. There also an invasive species, namely zebrafish (Amatitlania nigrofasciata) was found in this Lake. From the results of the study, we hope that the government in cooperation with the surrounding community, can control the ecological conditions of the waters of Beratan Lake, especially the presence of invasive species which are increasing in number, as well as protect endemic species.
 Keywords: Abundance; beratan lake; community structure; plankton; saprobity

Feeding and locomotor rhythm of the ornamental cichlid fish Amatitlania sp. in different social groups.

The aim of this study was to evaluate the feeding activity and the rhythm of daily locomotor activity of the convict cichlid (Amatitlania sp.) kept in different social groups under a self-feeding system. A total of 120 animals was distributed among six repetitions of four social groups, as follows: group 1 with one male and one female per tank; group 2 with three males and three females per tank; group 3 with six males per tank; and group 4 with six females per tank. Feeding activity (FA) and locomotor activity (LA) were evaluated using photoelectric presence-sensors connected to automatic feeders. The fish were fed a commercial extruded diet (46% crude protein and 3600 kcal kg-1 of digestible energy). Animal growth was evaluated for all groups. After 30 days of experimentation, the fish stabilized their demands by adjusting their consumption. Amatitlania sp. showed predominantly diurnal FA and LA. All groups showed a peak of activity when the light was turned on and when it was turned off. In summary, FA and LA of Amatitlania sp. are predominantly diurnal and independent of social group. Pairs and groups of males and females together consume less food in relation to groups of one sex or the other due to reproductive behaviour. On the other hand, groups of only males or females consume more food because they lack reproductive stimuli and thus prioritize growth. These results may support good feeding management practices for this ornamental cichlid. Studies relating feeding behaviour with different social groups are of great importance for determining effective feeding strategies for this species in captivity. Thus, such a study assists in a more efficient production of Amatitlania sp.

Predation Cues Lead to Rapid Changes in Brain Morphology of Juvenile Convict Cichlids (Amitatlania nigrofasciata)

Predation Cues Lead to Rapid Changes in Brain Morphology of Juvenile Convict Cichlids (Amitatlania nigrofasciata)

TESTING THE ENEMY RELEASE HYPOTHESIS IN THE INVASIVE FISH <i>AMATITLANIA NIGROFASCIATA</i> (PERCIFORMES: CICHLIDAE) IN MEXICO

The enemy release hypothesis (ERH) posits that invasive species are released from their natural enemies in their introduced 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 introduced 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 introduced range when it is infected with a low richness and diversity of helminths.

Effect of water temperature and food availability on growth performance, sex ratio and gonadal development in juvenile convict cichlid (Amatitlanianigrofasciata)

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.

Uncertain foraging opportunities and predation risk exert additive effects on induced neophobia in cichlids

Neophobia is defined as the avoidance of novel or unknown stimuli, including unknown predators, and can be induced by exposure to uncertain ecological conditions. In addition to uncertainty related to predation risk, uncertainty may also arise from increased foraging competition. Prey forced to spend time and energy competing for limited resources may not have enough time available to devote to predator identification and hence benefit from increased neophobia. Here, we tested the potential interaction of reduced foraging opportunities and elevated predation risk on the strength of neophobia (the antipredator response towards a novel chemical cue). In our first experiment, shoals of juvenile convict cichlids, Amatitlania nigrofasciata , were exposed to high (10% total body weight/day) or low (1% total body weight/day) relative food abundance for 7 days. During the final 3 days, we exposed the shoals to high versus low background predation risk, resulting in a 2 × 2 design. We found that while low food abundance alone and risk alone induced a weak neophobic response to a novel cue (versus water control), cichlids pre-exposed to high risk and low food abundance exhibited significantly a stronger neophobic response, in an additive pattern. In our second experiment, we exposed shoals of cichlids to a fixed amount of food distributed on a single (high competition) patch or across five (low competition) patches for 7 days, with the same risk manipulation as above for the final 3 days. As in experiment 1, we found that high competition alone and risk alone elicited a weak neophobic response to novel cues and that high risk and high competition had additive effects on the strength of induced neophobia among juvenile cichlids. Together, our results indicate that uncertainty of risk and of foraging opportunities exert additive effects on the phenotypically plastic neophobia among prey populations. • Neophobia should reduce costs of bad decisions under uncertain conditions. • Increased competition should increase uncertainty of foraging opportunities. • We exposed cichlids to high vs low predation risk under high vs low competition. • Neophobic responses were stronger under high competition. • Uncertain risk and foraging opportunities exert additive effects on neophobia.

Sex-specific prioritization of parental roles by the convict cichlid is differentially affected by brood predator threat

Abstract Parents are faced with multiple, critical tasks, and must prioritize mutually exclusive activities. With biparental care, decisions on prioritization become more complex, as sexes may differ in their prioritization of conflicting behaviours and compensation for changes in their mates’ behaviour. Here, I examined the decisions of biparental convict cichlids when they were forced to retrieve displaced young and defend against an intruder. The size and proximity of the potential predator was varied to determine how threat-level influenced prioritization decisions. Males tended to be consistent in their contributions to offspring, regardless of the threat to young. Female parents, however, were much more variable in their care and adjusted their aggression with the size of the intruder and adjusted retrieval in relation to the proximity of the offspring. Sex differences in parental contributions may be due to differences in the parents’ ability or willingness to adjust roles and/or differential potential future reproduction.

A potential role of nettle (Urtica dioica) extract on growth, biochemical changes and reproductive performance of convict cichlid (Amatitlania nigrofasciata).

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), 0.1g (NE0.1), and 0.5g (NE0.5) nettle extract per kilogram feed over 56days. The highest final weight (4.2 ± 0.1g), weight gain (2.8 ± 0.1g), 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 ± 6.5mgg-1), cholesterol (28.4 ± 3.3mgg-1), and triglyceride (211.5 ± 39.0mgg-1) levels. Total protein (36.3 ± 3.4mgg-1) and albumin (2.7 ± 0.1mgg-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 0.1g 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.

Urea Excretion and Arginase Activity as New Biomarkers for Nitrite Stress in Freshwater Aquatic Animals

Background: In recent years, the concern has been growing on increasing aquatic nitrite levels due to anthropogenic activities. Crustaceans and fish easily uptake nitrite via the chloride uptake system of gills. High nitrite body levels may interfere with nitric oxide (NO) production by nitric oxide synthase (NOS). The arginase, which catalyzes arginine conversion to ornithine and urea, is central to NO homeostasis. In vivo, changes in the arginase activity alter urea body levels and urea excretion and modulate NOS by altering arginine availability for NO synthesis. Excess arginase activity may uncouple NOS and induce oxidative stress. Methods: We tested muscle arginase activity and urea excretion in two fish species, zebrafish and convict cichlid, and the crustacean Yamato shrimp, under sub-lethal nitrite stress. Results: Exposure to nitrite (2 mM in the fish, 1 mM in the shrimp) significantly increased blood nitrite concentration in all species. Concomitantly, nitrite stress significantly increased arginase activity, urea excretion, and urea levels in the blood. In Yamato shrimp, urea levels also increased in muscle. Conclusion: Our results agree with the hypothesis that nitrite stress affects NO homeostasis by arginase stimulation and urea excretion. These parameters might function as markers of sub-lethal nitrite stress in freshwater fish and crustaceans.

Fighting can benefit both winning and losing male convict cichlid fish

AbstractFemale mate choice can involve a complex assessment process which is hypothesized to have evolved in order for females to maximize their reproductive success. In this laboratory experiment, we examined the mate choices of female convict cichlids (Amatitlania nigrofasciata) (who have an extended period of mate assessment and benefit from relatively long phases of biparental care) when presented a dichotomous choice between males that they had previously observed winning or losing a fight or novel males. When winner and loser males were presented to females together, females did not show a general preference for either male, but spent substantial time alone, away from both males. When the winner male was paired with a novel male, females showed an evident preference for the winner male. Females also showed an eventual preference for the loser male when paired with a novel male, but in this case, the female spent initially more time with the novel male before shifting to the loser male. In spite of losing their initial competition, loser males were attractive to females, more so than novel males, illustrating that participation in a fight observed by a female is beneficial to the male, even if he is not ultimately victorious.

Sex Differences in How Territory Quality Affects Aggression in Convict Cichlids.

SynopsisIn animal contests, the value an individual assigns to limited resources can directly impact the level of aggression it demonstrates. For territorial species, individuals often assess their territory quality and appropriately modify the time and energy invested in its defense. In this study, male and female convict cichlids, Amatitlania nigrofasciata, were acclimated to one of three territorial treatments representing either a low, medium, or high resource value. Territories with a “Low Value” included substrate alone, “Medium Value” territories included substrate and a nest site, and a “High Value” territory included substrate, a nest site, and constant food source. After three days of acclimation, a size-matched intruder was introduced to elicit territorial aggression and behaviors were observed. Territory quality affected one measure of low-intensity aggression (displays) in residents but had no effect on high-intensity aggression (bites and chases). Moreover, there was a significant effect of sex, with males and females differing in the types of aggressive behaviors demonstrated across all treatments. Females showed more low-intensity aggressive behaviors toward intruders than males did. Additionally, a significant interaction of sex and territory quality was observed on two measures of high-intensity aggressive behavior (bites and chases), with females more likely than males to increase aggressive behaviors along with increasing territory quality. This suggests that females may be more sensitive and/or responsive to changes in the quality of a territory, possibly due to the necessity of a suitable nest site for egg deposition within a territory.

Aggressive interactions and consistency of dominance hierarchies of the native and nonnative cichlid fishes of the Balsas basin.

Dominance hierarchies are generally established based on the levels of aggressiveness that animals present. Frequently, animals fight to establish a dominance hierarchy and obtain a disputed resource. The Mexican mojarra Cichlasoma istlanum is a native species of the Balsas river basin and coexists there with four nonnative cichlids: tilapia Oreochromis sp., convict cichlid Amatitlania nigrofasciata, spotcheek cichlid Thorichthys maculipinnis, and green terror Andinoacara rivulatus. These five cichlid species compete for spaces for reproduction, feeding, and shelter and frequently engage in aggressive interactions to obtain these resources. We quantified dominance indices to evaluate the hierarchical structure of dominance among these five cichlids and the duration of aggressive behaviors of the Mexican mojarra during experimental contests between the native species and each of the four nonnative species. The Mexican mojarra was consistently dominant over the other four cichlid species, performing a larger number of aggressive behaviors and investing more time in attacking than the nonnative cichlids, which resulted in a higher hierarchical position. Our results show that the native fish, Mexican mojarra, established dominance over all four nonnative cichlid fish of the Balsas basin. Thus, the establishment of nonnative cichlid species in the Balsas basin is likely associated with factors other than behavioral dominance.

Changes in an Exotic Fish Community Assemblage of a Thermal Spring in Central Idaho

Barney Hot Springs is a thermal spring in the headwaters of the Little Lost River drainage in central Idaho. Tropical fish have been released into Barney Hot Springs, and several species have established self-sustaining populations. The objectives of this study were to determine the current community assemblage of tropical fish in Barney Hot Springs and to assess species composition and extent of downstream distribution of tropical fish in Barney Creek. The composition in 2017 consisted of Amelanic Convict Cichlids Amatitlania nigrofasciata, Mozambique Tilapia Oreochromis mossambicus, Zebra Mbuna Maylandia zebra, and Green Swordtails Xiphophorus hellerii. Total abundance of all fish species was estimated at 12,043 fish (95% CI 9807–15,600), with Green Swordtails making up 68% of the population, Zebra Mbuna 20%, Convict Cichlids 9%, and Mozambique Tilapia 3%. In Barney Creek, fish were collected within 800 m of Barney Hot Springs. In March 2018, a rain-on-snow event occurred that resulted in a fish kill. In fall 2018 after this event, Convict Cichlids, Green Swordtails, and Goldfish Carassius auratus were collected. Overall abundance was estimated at 1972 fish (95% CI 1757–2227), with Green Swordtails and Goldfish each composing 50% of the population; no Convict Cichlids were recaptured, so abundance could not be estimated. In Barney Creek, fish were collected within 400 m of Barney Hot Springs. We documented current changes to the fish community assemblage of Barney Hot Springs and Barney Creek that were driven by colonization (i.e., introduction of aquarium fish) and by local extinction through species interactions and stochastic events. Currently, we do not know the impact that the introduced fish fauna of Barney Hot Springs may have on native species or ecosystem function.