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The Midas cichlid (Cichlasoma citrinellum) is an aggressive, monogamous fish living in the Great Lakes of Nicaragua. Its breeding success rates are low due to intense competition for breeding sites and high levels of predation on the young. Male Midas cichlids devote a small portion of body weight to gonads and gametes compared with females. Males produce relatively small amounts of sperm perhaps because cichlid fertilization is very efficient and the male has a high certainty of paternity. While pair members invest equal amounts of time in parental care over the course of the breeding cycle, there is a clear division of labor. Males invest more in territorial protection than do females, whereas females provide more nurturance. Both parents are active over the course of the cycle but the male invests more intensely in the early stages of the cycle. About the time the eggs hatch, the burden of care shifts to the female and she continues to invest significantly more than the male over the remainder of the cycle. Females invest much more than do males when tissue investment and parental behavior are combined. Females also assume more of the burden of care as the brood matures. The male is not free to take advantage of this and leave his mate to initiate other broods because two parents are needed to defend the breeding site and brood. Monogamy with biparental care results.

Summary Previous studies of parent-young interactions in cichlid fish have establish­ed some of the details of such relations, but have raised, or left unanswered many questions. In particular, there are questions as to the recognition of parents and young by each other, and to what extent learning might be involved in such recognition. Based on observations of exchanges of parents between families of Cichla­soma citrinellum, we suggest that parents learn to recognize young during each pare!1tal cycle. They appear to have a moderately short term memory for recognition of young, and accept young corresponding to this memory. Parental fish accept conspecific fry younger than, or the same age, but not those older than their own. Successive presentations of young fry maintained parental behavior for much longer than normal. Changes in color pattern, and some aspects of parental behavior are described. Zusammenfassung Fruhere Arbeiten uber Eltern-Kind-Beziehungen an Cichliden haben einige Details einer solchen Beziehung aufgezeigt. Unbeantwortet ist, wie Eltern und Junge sich gegenseitig erkennen und in wieweit ein LernprozeB an dies em Erken­nen beteiligt ist. Nach Beobachtungen uber den Austausch von Elternfischen zwischen Fami­lien von Cichlasoma citrinellum halten wir es fur moglich, daB die Eltern ihre Jungen wahrend jedes Brutzyklus neu kennen lernen. Sie scheinen eine Art Kurz­zeitgedachtnis fur das Erkennen der Jungen zu besitzen und nehmen nur Junge an, die diesem Gedachtnisinhalt entsprechen. Elternfische nehmen Jungfische der gleichen Art an, wenn sie gleich alt oder junger als die eigenen sind; altere Jungfische werden nicht angenommen. Bietet man standig junge Brut, erhalt sich das Brutverhalten sehr viellanger als normal. Anderungen des Farbmusters und einige Aspekte des Pflegeverhaltens sind be­schrieben.

The Midas cichlid is a monogamous, biparental species. It breeds in a highly competitive system where pairs have a low probability of raising fry to independence. Both parents must cooperate to retain the territory and protect the fry from predation. Previous experiments showed that females prefer large, aggressive and sexually experienced males as mates but males do not display any consistent preferences. Here I present the results of two experiments designed to see whether qualities preferred by females correlate with increased success in retaining territories and in providing parental care. Pairs with either large or aggressive males had an advantage in appropriating and holding a breeding territory; reproductive experience conferred no advantage in usurping a territory. Aggressive and reproductively experienced males had an advantage in defending the brood from predators of fry, but size had no effect. Thus, the qualities preferred by females confer advantages both in holding territories and in protecting fry. In contrast, males need not be selective because females, once in possession of a brood, defend it equally well regardless of size, aggressiveness, or reproductive experience. The system is one of mutually enforced monogamy based on female choice; females drive the system because they provide more investment than do males (combining gametes and time) and because this investment is a reliable resource to the male.

This study investigated the ability of nest-guarding convict cichlid (Cichlusomu nigrofusciaturn) females to recognize their own mate and to defend their brood effectively against strangers at night. Cichlids in the laboratory bred in nesting boxes made of Plexiglas. At the fry stage, various conspecific males were introduced, at night, into the nest box of brood-guarding females. Female reaction was observed with infrared equipment. If the introduced male was their own mate, females showed little reaction. If the introduced male was a stranger, females reacted by directing head shakes, tail beats, and pushes or bites at the intruder. The frequency of these acts was significantly higher in the presence of strangers than in the presence of mates; the frequency also rose significantly as the size of strangers increased. The two largest classes of strangers fought with the females. These fights included circling behaviour, but not mouth-locking. Some aspects of female behaviour suggested that mate recognition is based on short-range chemical cues and not on sound, size, or rapidly diffusing odours. Mate recognition in the nest, at night, is an example of non-visual communication in fish, and active nest defense at night shows that the convict cichlid, normally considered to be diurnal, can engage in coordinated and effective behaviour in the absence of light.

This study, examined influence of carrot (Daucus carota) and red pepper (Capsicum annuum) as natural pigment material on colouration of cichlid (Cichlasoma severum sp. Heckel, 1840). Mean weight of 120 fish were 1.16±0.22 g and they were divided into 3 groups with duplication each. Three types of experimental feed were prepared; the first group was added carrot, second one red pepper to provide 50 mg of total pigments kg-1 in diets and control feed do not have any pigment material. Fish were fed by 1% of their live weight and trial lasted for 50 days. Early in the trial, total carotenoid quantities were measured in carrot and red pepper, fish and their feeds and the end of it only in fish. Carotenoid amount in the fish samples by fed with red pepper and carrot diets were 5.25±0.90 and 5.60±0.29 mg g-1, respectively. Consequently a significant difference was found between individuals fed by natural pigment material and those by unpigmented feeds (p

An allochtonous cichlid fish Rocio octofasciata (Regan, 1903), new to Russian fish fauna, was identified and described in Staraya Kuban Lake, in the city of Krasnodar. An analysis of this species’ living conditions in various regions (within the native range, in the water bodies of the southern United States that it invaded, and in Staraya Kuban Lake) was carried out. It was suggested that this species formed a self-sustaining population in the lake, being completely naturalized. Further studies of this alien fish species in Staraya Kuban Lake were proposed.

Phylogenetic relationships among cichlasomatine cichlids were studied using an extensive taxon sampling and both morphological and molecular data sets. A new genus, Andinoacara n. gen. with six species (A. pulcher-rivulatus group of previous authors) from trans-andean South America and NW cis-andean South America, is described based on results of phylogenetic and diagnosability analyses and tests of alternative topologies Our results demonstrate that cichlasomatine cichlid diversity is divided into five principal lineages composed of eleven genera and three suprageneric clades: the [(Bujurquina, Tahuantinsuyoa), (Andinoacara) (BAT) clade; the (Cleithracara, (Nannacara, Ivanacara)] clade (NIC) plus Laetacara and ′Aequidens′ hoehnei; and the (Aequidens, Cichlasoma) clade, where Aequidens is paraphyletic to Cichlasoma. Two former Aequidens species are additionally transferred into Krobia (K. potaroensis, K. paloemeuensis). ′Aequidens′ hoehnei probably represents a unique evolutionary lineage and would thus qualify for a separate generic status. Molecular data are yet not available for this species and its generic status requires further study. Relationships between the three suprageneric clades and between Acaronia and Krobia could not be convincingly resolved with our data set of two mitochondrial (16S and cyt b) and two nuclear (S7 and RAG1) molecular markers and 96 morphological characters. Zusammenfassung Die phylogenetischen Beziehungen der cichlasomatinen Cichliden wurden anhand einer umfangreichen Artenauswahl mittels morphologischer und molekularer Datensatze ermittelt. Die neue Gattung, Andinoacara n. gen. (von fruheren Autoren als A. pulcher-rivulatus Gruppe bezeichnet) mit sechs Arten aus dem westandinen Sudamerika und dem nordwestlichen ostandinen Sudamerika wird basierend auf phylogenetischen und diagnostischen Analysen sowie Tests alternativer Topologien beschrieben. Unsere Ergebnisse zeigen, dass die Vielfalt der cichlasomatinen Cichliden in funf prinzipiellen Linien mit elf Gattungen und drei Kladen (uber Gattungsebene) aufgeteilt ist. Das sind: der ((Bujurquina, Tahuantinsuyoa), Andinoacara) Kladus (BAT); der (Cleithracara, (Nannacara, Ivanacara)) Kladus (NIC) mit Laetacara und `Aequidens' hoehnei sowie der (Aequidens, Cichlasoma) Kladus. Zwei ehemalige Aequidens-Arten (K. potaroensis, K. paloemeuensis) werden in die Gattung Krobiauberfuhrt. `Aequidens' hoehnei stellt wahrscheinlich eine einzigartige evolutionare Linie dar, die eine eigenstandige Gattung rechtfertigt. Molekulare Daten liegen hierfur jedoch nicht vor, sodass weitere Untersuchungen notwendig sind. Die verwandtschaftlichen Beziehungen der drei Kladen (oberhalb Gattungsebene) und zwischen Acaronia und Krobia konnten mit unseren Datensatzen aus den zwei mitochondrialen (16S and cyt b) und den zwei nuklearen (S7 and RAG1) molekularen Markern und den 96 morphologischen Merkmalen nicht uberzeugend geklart werden.

Dietary carotenoids of various types and concentration can affect the pigmentation efficiency in an ornamental fish red devil, Cichlasoma citrinellum. Astaxanthin (AX) containing alga Haematococcus pluvialis, a synthetic AX, and a synthetic β-carotene (BC) were supplemented in formulated diets at two concentrations, 80 and 160 mg kg−1, resulting in six pigmented diets. Formulated diet without carotenoids supplementation served as a control. These diets were fed to the fish, for 8 weeks. Astaxanthin dominated in body carotenoids deposition. Dietary BC hardly had contribution to body AX. Control fish had much lower AX content in skin, fin and muscle than fish fed pigmented diets, but had equal AX content in liver, intestine and gonad as those fish. Dietary synthetic AX had equal efficiency in depositing AX in skin and fin as natural AX but higher efficiency in gonad than natural AX. Fish fed AX supplemented at 160 mg kg−1, either natural or synthetic AX, had higher AX content in skin than fish at 80 mg kg−1 but had equal AX content in fin as fish at 80 mg kg−1. Disregarding the treatment effects, the overall average AX content in tissue in descending order was gonad>fin≧(intestine=skin)>liver>muscle.

A new nematode species, Philometra poblana n. sp., is described based on specimens recovered from skin at the base of the pectoral fins of the cichlid Cichlasoma istlanum (Jordan and Snyder, 1899) from the water spring El Borbollon, in the State of Puebla, Mexico. The new species most closely resembles Philometra gymnosardae and Philometra ophisterni; however, P. poblana can be easily differentiated from the other species by the length of gravid females (7.10–10.43 vs. 14.8– 27.0 and 28.67–39.30 mm, respectively), length of caudal projections (0.015–0.023 vs. 0.047 and 0.006–0.009 mm high, respectively), site of infection (skin at base of pectoral fins vs. abdominal cavity, both species), and the host species (Cichlidae vs. Synbranchidae and Scombridae).

Many characteristics of the South American teleost fish Cichlasoma dimerus (body size, easy breeding, undemanding maintenance) make it amenable to laboratory studies. In the last years, many of the fundamental aspects of its reproductive and developmental biology have been addressed in our laboratory. Rather recently, the immunohistochemical localization of pituitary hormones involved in reproduction and in background color adaptation has been described in both adult and developing individuals, and the role of FSH in ovarian differentiation has been established. These findings have been correlated with mapping of some of their brain-derived controlling hormones. The latter include brain-derived gonadotropins which were shown to be active in vitro in the control of pituitary hormone secretions. The emerging picture shows C. dimerus as an interesting species in which many of their basic features have already been investigated and which conform a solid platform for comparative studies correlating neurohormones, pituitary hormones and behavior, from the molecular to the organismic level.

Located within Mexico’s Montes Azules Biosphere Reserve, the Tzendales River is part of the Usumacinta River Basin, which supports the largest diversity of cichlid fishes in Middle America. We evaluated temporal and spatial variation of species richness and distribution of cichlids in the Tzendales River; we collected 14 species with nine native and five endemic. The species with greatest relative abundances and broadest spatial distributions were Vieja intermedia and Amphilophus nourissati; and the rarest and most spatially restricted species were Thorichthys meeki and Parachromis friedrichsthalii. Environmental characteristics varied seasonally although fish assemblages and distributions were relatively stable over time. Based on habitat use patterns, three species associations were observed: (1) Amphilophus nourissati, Petenia splendida, Vieja argentea, V. bifasciata, V. intermedia, V. pearsei, V. synspila and V. ufermanni; (2) ‘Cichlasoma’ salvini and Parachromis friedrichsthalii; and (3) Thorichthys helleri and Thorichthys meeki. Two rheophilic species, Theraps lentiginosus and Theraps irregularis, had low habitat overlap with all of the other cichlid species. Canonical correspondence analysis showed that the depth, current speed and quantity of rocks in the substrate defined the spatial distribution of species in dry season. Cichlids of the Tzendales River appear to partition habitat in a manner that reduces resource competition.

An herbivorous cichlid fish Cichlasoma (Theraps) nicaraguense has been reported to perform brood care for the fry of a piscivorous cichlid Cichlasoma (Nandopsis) dovii in a Nicaraguan lake. It was suggested that interspecific brood care (IBC) evolved to propagate C. dovii as a predator of another herbivorous fish Neetroplus nematopus, which is superior to C. nicaraguense in competition for breeding territory. However, it is still unclear how IBC is maintained in the face of cheaters that do not provide IBC. In this study, to elucidate the conditions for maintenance of IBC, we developed a spatially structured model, assuming a trade-off between reproduction and IBC (i.e., intra- and interspecific competition) and behavioral plasticity in IBC. The model predicted the following maintenance conditions: the probability of expressing (or suppressing) IBC in response to competitor invasion (or exclusion) is low, or, if the probability is high, then IBC is less effective for exclusion of competitors. Furthermore, we also predicted that IBC can be maintained without spatial structure if it is plastic behavior. Our model contributes to understanding of maintenance of IBC by providing empirically testable predictions. We discuss how this model is applicable to more general relationships, such as those in competitive or mutualistic systems.

A new species of Crassicutis Manter, 1936 is described from the Sinaloan cichlid Cichlasoma beani (Jordan) (Osteichthyes: Cichlidae) in the upper Río Santiago basin. Crassicutis choudhuryi n. sp. differs from most of the other nominal species by having testes located in a symmetrical position. The only other species of the genus that includes some specimens exhibiting this trait is Crassicutis intermedius (Szidat 1954), a species found in 5 species of siluriforms and 1 species of characiform in South America. However, this species differs from Cr. choudhuryi n. sp. by having testes almost half of the size, and vitelline follicles extending anteriorly to the region between the acetabulum and the intestinal bifurcation. The new species is morphologically very similar to Crassicutis cichlasomae Manter, 1936, but clearly differs from this species because of the constantly symmetrical position of the testes. Additionally, Cr. choudhuryi n. sp. is found in the Santiago River basin on the Pacific slope of Mexico, parasitizing specifically the endemic Ci. beani that does not co-occur with any other cichlid. Cr. cichlasomae exhibits more hosts (about 25 species of cichlids only in Mexico) and a wider distribution range that extends from northeastern Mexico southward to Central America, Cuba, and Brazil. To corroborate that our specimens were not conspecific with Cr. cichlasomae, sequences of the internal transcribed spacer (ITS1) and the 28S ribosomal RNA genes of individuals from several populations (recently collected in southeastern Mexico) were obtained and compared to the species described herein. Sequence divergence (1.3% for the 28S and 4.0% for the ITS1) gives further support to the erection of a new species.

In this study, we have investigated the effects of Porphyridium cruentum (Rodophyta) as a natural pigment source and astaxanthin and β-carotene as synthetic pigment sources on the skin colour of cichlid fish (Cichlasoma severum sp., Heckel 1840), which are generally light orange with white patches and becomes shiny orange in the reproductive phase. The fish were fed diets containing 50 mg kg−1 astaxanthin and β-carotene, and P. cruentum powder. The amount of both natural and synthetic pigment sources given as feed was 50 mg kg−1, and the experiment was continued for 50 days. Total carotenoid content of the fish was determined spectrophotometrically at the end of the experiment. As a result, while a visible change of colour in the skin of the fish fed on the feed containing astaxanthin was observed with 0.34 ± 0.2 mg g−1 of pigment accumulation, a relatively small change of colour was observed in the skin of other fish that were fed on the feed containing P. cruentum and β-carotene with 0.22 ± 0.2 mg g−1 and 0.26 ± 0.1 mg g−1 of pigment accumulations, respectively. Therefore, it was determined that these pigment sources have an effect on the colour of cichlid fish.

Two monotypic Neotropical cichlid genera, Hypsophrys Agassiz 1859 and Neetroplus Gunther 1867, are well known but poorly diagnosed. The possession of a single supraneural (versus two for most Middle American species), a strongly rounded snout with a small and slightly subterminal mouth (versus straight snout profiles with terminal mouth) provide morphological support for the sister-group relationship of Hypsophrys and Neetroplus recovered in recent molecular phylogenetic analyses. Based on these shared features Neetroplus is synonymized with Hypsophrys . In addition, the senior synonym Hypsophrys unimaculatus should no longer be improperly suppressed in favor of the more familiar, but junior, H. nicaraguensis.

We have examined the effects of Tribulus terrestris (TT), a non-toxic herb, on sex reversal in the Convict Cichlid Cichlasoma nigrofasciatum with the aim of introducing a new environmentally friendly method for masculinization in C. nigrofasciatum. TT is a natural plant product that elevates the testosterone levels in humans and animals. Different concentrations (0.0, 0.10, 0.20 and 0.30 g/l) of TT extract were tested for their effect on sex reversal in C. nigrofasciatum by immersing newly hatched offspring once weekly for 2 months in TT extract. Of the dosages used in the present study, 0.30 g/l TT was the most effective in terms of masculinization, resulting in a maximum male ratio of 87.23% (P 0.05). We concluded that TT had no negative effect on the survival rate of C. nigrofasciatum. In addition, all groups of TT-treated fish exhibited successful growth acceleration compared to the control group, but only the 0.30 g/l TT treatment significantly improved the growth rate of C. nigrofasciatum. (P

We report on the occurrence and possible establishment of a non-native cichlid fish in a brackish-water system in the lower Chao Phraya River delta region, Thailand. Although, the possibility of some degree of introgressive hybridization can not be ruled out, Thailand specimens agree best with Mayan Cichlid “Cichlasoma” urophthalmus (Gunther 1862). Our collections represent the first records of this New World, highly-invasive, euryhaline fish from Thailand and coincides with recent collections from Singapore. Positive identification of specimens as “C.” urophthalmus requires caution due to the diversity of the Cichlidae (>1,300 species), widespread introduction of many family members, variation within species, extensive interspecific overlap in characters, and proliferation of artificial cichlid hybrids (e.g., Flowerhorns). We first became aware of the Thailand population in 2005 when “C.” urophthalmus began appearing in the catches of local fishermen. We visited the site in November 2006 and obtained and examined voucher specimens. The abundance and wide size range of juveniles and adults in local ponds and an adjacent canal is evidence of natural reproduction. Because water bodies throughout the Chao Phraya delta are interconnected and subject to flooding, it is likely that “C.” urophthalmus is already established and is dispersing, but surveys and monitoring are needed to determine their exact geographic range. The Thailand population is compared to “C.” urophthalmus introduced into Florida (USA). Based on what is known about Florida “C.” urophthalmus, it is predicted that this cichlid will further invade coastal and inland waters in Thailand and elsewhere in Southeast Asia. This cichlid has a long history in the aquarium trade in Europe. However, there are no records from the wild in European waters and, because of the colder climate, the possibility of establishment in that region is relatively low.

Even though genetic aspects of some cichlids have been widely studied over the last decades, little is known about the genomic structure of Cichlidae when compared to the large number of species in the family. In this paper, the first chromosomal data for Cichlasoma sanctifranciscense Kullander, 1983 are presented and discussed based on cytotaxonomic and karyoevolutionary inferences on Cichlasomatini. All individuals shared a diploid number of 2n=48 distributed as 10sm+28st+10a and Ag-NORs on short arms of a submetacentric pair. Heterochromatin was detected at pericentromeric regions of most chromosomes and at terminal sites of a few pairs. GC-rich regions were observed on short arms of two biarmed pairs, including the pair bearing Ag-NORs. Double-FISH with ribosomal probes revealed 18S rDNA clusters coincident with GC-rich regions in two biarmed pairs and 5S rDNA at interstitial location of an acrocentric pair. Cichlasoma sanctifranciscense shares some symplesiomorphic traits described in Cichlidae (2n=48 and pericentromeric C-bands) while other chromosomal features diverge from the common trend reported in Cichlasomatini, such as multiple 18S rDNA sites combined with high FN values. Finally, the present results are useful to support taxonomic identification once species-specific markers have been provided in Cichlasoma sanctifranciscense.

The ‘Cichlasoma’ facetum group is part of the taxonomically complex group of Neotropical cichlid fishes of the tribe Heroini. Many species groups and unplaced species of heroines are still left without a generic name following the revision of the genus Cichlasoma. We describe here the ‘Cichlasoma’ facetum group as a new genus, Australoheros, and provide evidence for its monophyly based on phylogenetic analyses of morphological and mtDNA characters. Australoheros is morphologically characterized by the lowest values in meristic characters among heroines and by three apomorphic characters in coloration pattern. In addition to the three described species of Australoheros, our results of species delimitation based on a combination of tree‐ and character‐based approaches identify seven putatively new species of Australoheros. Several coding schemes of morphological characters are used to recover the intrageneric relationships within the genus, resulting in very similar topologies. Discovery of additional species within the genus is expected once material from the whole distribution area is studied.

We evaluated diet and morphology through ontogeny for a freshwater population of the Mayan cichlid ‘Cichlasoma (Nandopsis)’ urophthalmus (Gunther 1862) in Florida’s Big Cypress National Preserve. This species is a generalist predator throughout ontogeny. Fish remained the primary prey item throughout ontogeny, but there was a shift from detritus and ostracods among juveniles to algae, gastropods (snails), decapods, Hymenoptera, and adult Diptera among adults. All morphological variables grew isometrically except total molariform tooth area and pharyngeal jaw mass, which exhibited positive allometry. Despite a moderately robust adult pharyngeal jaw apparatus, this species does not specialize on hard prey at this south Florida site. Compared to its native range in Mexico, fish in Florida have undergone a pronounced niche shift with the diet being dominated by fish and snails, probably due to greater availability. The invasive success of C. urophthalmus does not appear to be related to ontogenetic morphological shifts or dietary specialization. Rather, its successful and rapid colonization of southern Florida might in part be related to its generalized and opportunistic feeding habits and morphology.

The divergence of progeny from the same spawners of Cichlasoma nigrofasciatum into two groups by duration of embryogenesis and the level of motor activity was studied close to the end of the embryonic period. Free embryos were also studied. During the study, eggs were treated with agents, modifying the activity of catecholaminergic and cholinergic systems. 3-Hydroxytyramine and L-Tyrosine were found to exert a weak influence on embryonic motility. After hatching, these substances modify swimming performance of free embryos, approximating movements of fish at later stages. 6-Hydroxydopamine and, still more, alpha-Bungarotoxin, decrease embryonic motility and postpone the hatching. The influence of these substances on the development of embryo motility increases during early ontogenesis, as indicated by decreased concentration of the substance, necessary for adequate reaction. Neither L-Tyrosine nor 6-Hydroxydopamine influenced the divergence of the progeny into two groups. Injection of the perivitelline fluid with high concentration of hatching enzyme from pre-hatching embryos into the perivitelline space of earlier embryos was found to induce the appearance of rotation movements, typical for more advanced embryos. Changes of correlation between the miogenic and neurogenic motor activity during early development of fish are discussed.

We isolated and characterized 18 microsatellite loci from the Mayan cichlid, Cichlasoma urophthalmus. Loci were screened for 24 specimens from a total of seven sites in south Florida, Mexico, Belize and Honduras. The number of alleles per locus ranged from 3 to 21, observed heterozygosity ranged from 0.208 to 0.875, and the probability of identity values ranged from 0.012 to 0.203. These new loci will provide tools for identifying the source population(s) for the introduction of Mayan cichlids in south Florida and for comparing population genetic structure of Mayan cichlids within and among subpopulations in its native (Central America) and introduced ranges (south Florida). Mayan cichlids are an invasive species in south Florida so identifying source populations may reveal pathways that can be managed to prevent further introductions. Mayan cichlids may also be useful as a model system in which to examine the relationship between introduction history, population genetic diversity, and invasibility.

‘Cichlasoma’ scitulum, new species, is described from the Rio Rosario drainage in the Rio de La Plata region of Uruguay, and from lower Rio Uruguay tributaries in Argentina, Uruguay and Brazil. It is easily distinguished from the other two species of the ‘Cichlasoma’ facetum group in meristic and coloration characters. ‘Cichlasoma’ scitulum has the highest anal-fin spine counts of the three species and it is also characterized by having black-spotted dorsal, anal and caudal fins and flank and opercular scales. Steatogenys ocellatus e descrita como uma especie nova proveniente de localidades proximas as cidades de Tefe (Brasil) e Iquitos (Peru) na Bacia Amazonica. Esta especie e descrita com base em caracteristicas de morfologia externa, dados meristicos, pigmentacao, osteologia e propriedades das descargas do orgao eletrico (DOE). Steatogenys ocellatus diferencia-se das duas outras especies do genero, S. elegans e S. duidae, pelas seguintes caracteristicas: (1), tamanho maximo do corpo relativame...

In this study, I investigate body-form variability in the trophically polymorphic Cuatro Cienegas cichlid, Cichlasoma minckleyi. I use geometric morphometrics to assess and compare size, shape, and allometric patterns within and between dental morphs (distinguished by differences in pharyngeal bones and papilliform or molariform dentitions). I find that dental morphs do not differ significantly in size, shape, or allometric slopes, but do differ in allometric intercepts; thus, dental morphs exhibit different patterns of body-form variability. Within each morph, body-form varies between more fusiform 'piscivores' and deeper-bodied dietary generalists. However, papilliform individuals show a continuous distribution of body-forms, whereas molariform individuals exhibit a discontinuity. I compare results from geometric analyses with those from a traditional (distance-based) morphometric analysis, finding that geometric techniques more clearly recognize discontinuities in shape. Finally, I suggest explanations for observed differences in body-form variability between dental morphs, concluding that the best explanation hinges on the relative importance of genetic and environmental factors in influencing body-form.

In a survey of epigean and cave streams in the Sao Domingos karst area, 38 species were present in the stream reaches, including 10 characiforins, 19 siluriforins, seven gymnotiforms and two pereiforms. One species of Astyanax and the new armoured catfish species Parotocinclus were the most common epigean fishes in Sao Domingos. The most conspicuous non-troglomorphic cave fishes were Hoplerythrinus unitaeniatus, Astvanax sp., Brycon sp. and two species of Imparfinis, with I. hollandi being the most common fish in most caves. Sao Domingos karst area has the most diverse and abundant Brazilian cavefish fauna, not only in terms of troglobitic species but also in general fish richness. with 22 non-troglomorphic species recorded in caves in addition to five troglobitic ones. Most fishes examined for stomach contents had at least partially full stomachs. The studied fishes were carnivorous, feeding primarily on aquatic insects. Fishes with developed gonads recorded in caves were I. hollandi, Rhamdia quelen, Pseudocetopsis plumbeus, Hoplerythrinus unitaeniatus and Cichlasoma araguaiensis, indicating a potential for reproduction in the subterranean habitat.

The endemic cichlids of the Cuatro Cienegas Basin, Coahuila, Mexico are currently grouped in a single polymorphic species, Cichlasoma minckleyi. Two morphs of C. minckleyi were distinguished largely by features of the trophic apparatus, especially the pharyngeal dentition. Variation in body shape, based upon analysis of a set of linear measures, was continuous and did not allow recognition of discrete morphs. Individuals raised in the laboratory on several different diets indicated that trophic morphology had an important genetic component. Individuals raised in the laboratory, however, did not differentiate to the degree seen in comparably sized individuals collected at Cuatro Cienegas. This may be because snails used as food in the experiments were not as hard as endemic snails and indicated that some aspects of trophic morphology were also dependent upon environmental cues.

A new nematode species, Atractis vidali sp. n., is described from the intestine of cichlid fishes, Vieja intermedia (Günther) (type host) and Cichlasoma pearsei (Hubbs), from specimens collected in three localities in the Mexican states of Campeche (Santa Gertrudis Creek) and Chiapas (Cedros and Lacanjá Rivers). It differs from the only other atractid species reported in fishes of Mexico, Atractis bravoae, mainly in possessing two very unequal spicules. In contrast to the 10 species parasitising amphibians and reptiles in America, the new species has a longer body, spicules and a gubernaculum, and a different distribution of the caudal papillae. This is the second species of the genus Atractis recorded from freshwater fishes.

Individuals that dare approach predators (predator inspection behaviour) can reduce their overall risk of predation by engaging in attack cone avoidance. Under laboratory conditions, we investigated the interaction between predator diet and prey experience with predators in attack cone avoidance during predator inspection visits by glowlight tetras,Hemigrammus erythrozonus (Characidae, Ostariophysi). Shoals of predator-experienced versus predator-naive glowlight tetras were exposed to live Jack Dempsey cichlids, Cichlasoma octofaciatum, that had been fed a diet of tetras (possessing an alarm pheromone) or swordtails, Xiphophorus helleri (lacking a recognizable alarm pheromone). Naive tetras exposed to tetra-fed predators significantly increased their antipredator response (increased shoaling, dashing and freezing) and altered their predator inspection behaviour (increased latency to respond, decreased rate of inspection and decreased inspecting group size) compared with naive tetras exposed to swordtail-fed predators. In addition, naive tetras exposed to tetra-fed predators directed significantly greater proportions of their inspection visits towards the tail versus the head of the predator (attack cone avoidance) versus naive tetras exposed to swordtail-fed predators. Experienced tetras, regardless of predator diet, also significantly increased antipredator responses and altered their inspection behaviour. Experienced tetras also displayed significant attack cone avoidance. These data suggest that both predator diet and prey experience play a significant role in the threat-sensitive mediation of predator inspection behaviour in prey fish. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Many prey organisms will approach (inspect) potential predators, primarily to assess local risk of predation. It has been demonstrated that Ostariphysan prey fishes can detect conspecific alarm pheromones in the diet of potential predators and use this chemical information to reduce their risk of predation while still gaining significant benefits associated with predator inspection. We conducted the current study to examine the possible effects of mixed diets on the use of these chemical predator diet cues during inspection visits. Shoals of four glowlight tetras (Hemigrammus erythrozonus) were exposed to Jack Dempsey cichlids (Cichlasoma octofaciatum) which had been fed diets consisting of: 100% tetras (with alarm pheromone); 75% tetra, 25% swordtail (Xiphophorus helleri, which lack a recognizable alarm pheromone); 25% tetra, 75% swordtail; or 100% swordtails. Tetras significantly increased their anti-predator behaviour in response to predators fed 100% tetra or the two mixed predator diets, but not when exposed to predators fed a 100% swordtail diet. Likewise, we observed significant differences in inspection behaviour. Tetras took longer to initiate an inspection, inspected in smaller groups and directed a greater proportion of inspection visits towards the tail region of the predator when it had been fed 100% tetra or either of the two mixed prey diets. We found no significant differences in either anti-predator or inspection behaviour among the three diet treatments containing tetras. These data strongly suggest that glowlight tetras are capable of detecting relatively small amounts of conspecific alarm pheromone in the diet of potential predators and that they modify their behaviour based on the presence or absence of these cues.

The behavioral significance of color patterns has been widely investigated in cichlid fishes (Perciformes; Cichlidae), whereas the ontogeny of cichlid color patterns has received less attention. We examined the ontogeny of melanistic pattern elements in the convict cichlid, Cichlasoma nigrofasciatum. Live juvenile convict cichlids, from hatching through age 88 days, were photographed using a dissecting microscope. Based upon this photographic record, we have characterized the sequential, intermediate phases of color pattern development in the convict cichlid. Convict cichlid fry hatch three days postfertilization with (horizontal) stripes and diffuse cranial and ventral chromatophores. Vertical bars develop gradually and are initiated as midlaterally incomplete semibars. This pigment pattern ontogeny appears similar to some, but not all, previously characterized cichlids.

Fishes such as minnows in the superorder Ostariophysi possess specialized alarm substance cells (ASC) that contain an alarm cue. Alarm substance can only be released by damage to the epidermis; thus, the release of alarm substance is a reliable indicator of predation risk. When nearby minnows detect the cue, they adopt a range of antipredator behaviors that reduce their probability of predation. Predator–predator interactions afford prey an opportunity to escape and, thus, a fitness benefit that maintains alarm substance calls over evolutionary time. Here, we present data from a simple field experiment verifying that nearby predators are attracted to minnow alarm substance because it signals an opportunity to pirate a meal. Fishing lures were baited with sponge blocks scented with either (1) water (control for sponge odor and appearance), (2) skin extract from non-ostariophysan convict cichlids (superorder Acanthopterygii, Archocentrus “Cichlasoma” nigrofasciatus) to control for general injury-released cues from fish, or (3) skin extract from fathead minnows (superorder Ostariophysi, Pimephales promelas). Predator strike frequency on each sponge type was 1,1, and 7 for water, cichlid, and minnow cues, respectively. These data provide the first field test using fish predators of the predator-attraction hypothesis for the evolution of Ostariophysan alarm substance cells.

Made available in DSpace on 2015-10-21T20:34:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-01-01. Added 1 bitstream(s) on 2015-10-22T09:47:59Z : No. of bitstreams: 1 S1984-29612015000100012.pdf: 1086379 bytes, checksum: 2fef66298a8d95e81e70d5ceaa56a5ca (MD5) O objetivo deste estudo foi avaliar a prevalência e distribuição sazonal das principais espécies de parasitas em ciclídeos ornamentais amazônicos que afetam seu comércio. O estudo foi realizado entre agosto de 2007 e setembro de 2009. Foram amostrados 3042 espécimes de 9 espécies diferentes, das quais 9,47% tinham pelo menos um tipo de parasita externo. Na estação seca, ocorreram 81,25% dos casos. Crenicichla anthurus (28,57%) foi o mais parasitado, seguido por Aequidens diadema (26,32%), Pterophyllum scalare (22,69%), Cichlasoma sp. (9,52%), Apistogramma sp. (3,88%), e Symphysodon aequifasciatus (3,66%). Monogenea foi o grupo mais abundante de parasitas, ocorrendo em 66,67% dos casos. Na estação seca, ocorreram 96,88% deles. Este parasita infestou 95,68% dos casos em Pterophyllum scalare, 76,67% em Apistogramma sp., 33,33% em Cichlasoma sp. e 23,81% em Symphysodon aequifasciatus. Ichthyophthirius multifiliisinfestou 100% dos casos em Aequidens diadema, 76,19% em Symphysodon aequifasciatus, 66,67% em Cichlasoma sp., 41,67% em Crenicichla anthurus e 23,33% em Apistogramma sp.; Myxosporidia infestou 58,33% dos casos em Crenicichla anthurus; Trichodina infestou 4,32% dos casos em Pterophyllum scalare. A prevalência desses parasitas está relacionada com a época do ano, hábitat preferido, comportamento dos peixes, suscetibilidade individual e manejo dos animais durante o transporte pelos pescadores. The aim of this study was to evaluate the prevalence and seasonal distribution of the main parasite species in Amazonian ornamental cichlids that affect their trade. The study was conducted from August 2007 to September 2009. We sampled 3042 specimens from 9 different species, of which 9.47% had at least one type of external parasite. 81.25% of the cases occurred in the dry season. Crenicichla anthurus (28.57%) was the most parasitized, followed by Aequidens diadema (26.32%), Pterophyllum scalare (22.69%), Cichlasoma sp. (9.52%), Apistogramma sp. (3.88%) and Symphysodon aequifasciatus (3.66%). Monogenea was the most abundant group of parasites, occurring in 66.67% of the cases, of which 96.88% occurred in the dry season. This parasite infested 95.68% of Pterophyllum scalare, 76.67% of Apistogramma sp, 33.33% of Cichlasoma sp. and 23.81% of Symphysodon aequifasciatus cases. Ichthyophthirius multifiliis infested 100% of Aequidens diadema, 76.19% of Symphysodon aequifasciatus, 66.67% of Cichlasoma sp, 41.67% of Crenicichla anthurus and 23.33% of Apistogramma sp cases. Myxosporidia infested 58.33% of Crenicichla anthurus. Trichodina infested 4.32% of Pterophyllum scalare. The prevalence of these parasites is related to the season, preferred habitat, fish behavior, individual susceptibility and handling of animals during transportation by fishermen. Univ Estadual Paulista, UNESP, Aquaculture Ctr, BR-14884900 Jaboticabal, SP, Brazil Univ Estadual Paulista, UNESP, Coll Agr Sci &Vet, Dept Anim Pathol, BR-14884900 Jaboticabal, SP, Brazil Univ Estadual Paulista, UNESP, Coll Agr Sci &Vet, Dept Microbiol, BR-14884900 Jaboticabal, SP, Brazil Aquaculture Center, Universidade Estadual Paulista – UNESP, Jaboticabal, SP, Brazil Department of Animal Pathology, College of Agricultural Sciences and Veterinary, Universidade Estadual Paulista – UNESP, Jaboticabal, SP, Brazil Department of Microbiology, College of Agricultural Sciences and Veterinary, Universidade Estadual Paulista – UNESP, Jaboticabal, SP, Brazil

Convict cichlid Cichlasoma nigrofasciatum adults of the melanistic morph usually accepted fry of the same colour morph provided these were of approximately the same age and size as those of the receiver pair, whereas older and considerably younger fry were rejected or eaten. Xanthoric fry were usually accepted and rejected to the same extent as fry of their own colour morph. However, in certain combinations, especially when alien fry were 3 weeks old and the adopting parents already had their own 2 week old fry, fry of their own colour morph were significantly more likely to be adopted.

Red-parrot fish (male midas cichlid Cichlasoma citrinellum × female redhead cichlid C. synspilum) is one of the most important tropical fish in Taiwan. In high-density culture, poor water quality often induces emaciation, gill filament ulceration, gill opercula malformation, and high mortality. In an effort to solve these problems in a high-density culture environment, two bacteria, Bacillus subtilis and B. megaterium, were added to the recirculating-water systems of the grow-out facilities. The addition of Bacillus held total ammonia nitrogen concentrations to 5.4 mg/L or less and chemical oxygen demands to 40.8 mg/L or less; it also maintained the transparency of the recirculated aquarium water at 30–50 cm. Survival rate and quality of fish were dramatically improved with this microbial water quality management process. This method is easy to perform and can be adapted effectively in the commercial culture of red-parrot fish.

Many prey organisms will approach (inspect) a potential predator, primarily to assess local risk of predation. It has been argued that by avoiding the head region of predators during inspections, prey can reduce the risks associated with such behaviour (attack cone avoidance). Prior experiments, however, have not incorporated the combined chemical and visual predator cues. We conducted laboratory experiments to determine the effects of combined predator dietary (chemical) and visual cues on the form and location of predator inspection visits by glowlight tetras (Hemigrammus erythrozonus). Tetras were exposed to a live cichlid predator (Cichlasoma octofasciatum) which had been fed tetras (with alarm pheromone), swordtails (Xiphophorus helleri; lacking Ostariophysan alarm pheromones) or food deprived. There was no significant difference in the overall rate of predator inspection by tetras to tetra-fed, swordtail-fed or food deprived cichlids. There was, however, a significant effect of predator diet on the size of inspection shoals and the location of inspections. Tetras inspected a tetrafed predator in significantly smaller groups, more often as singletons and directed a greater proportion of their inspections towards the tail of the predator. Tetras exposed to swordtail-fed or food deprived cichlids inspected in larger groups and directed more inspections towards the head of the predator. When the predator dietary cue contained tetra alarm pheromone, there was a significant increase in the attack latency by predators. Taken together, these data suggest that tetras use both chemical and visual predator cues during inspection visits and will modify their behaviour based on the presence or absence of conspecific alarm pheromone in the diet of a potential predator.

Two populations of the piscivorous fish Gobiomorus dormitor (the ‘guabina’) were examined in two separate crater lakes in Nicaragua, Central America. At Lake Apoyo, G. dormitor were introduced in May 1991 by local fishermen and have invaded successfully; at Lake Xiloa, the population is naturally occurring. To provide baseline life history data for G. dormitor in both lakes and to test hypotheses related to population growth and invasion success, this study aimed to (1) document and define the population growth and depth distribution of the fish through video transects in Lake Apoyo; (2) compare diet composition between lakes; and (3) compare life history parameters between lakes, including relative growth rates and reproduction. Videotaped transect studies, designed originally to examine cichlid breeding, began in both lakes in 1990 and have documented the subsequent increase of G. dormitor. Yearly means generally fit the exponential growth model. G. dormitor foraged mainly in shallow waters in Lake Apoyo and preyed mostly upon the atherinid Melaniris cf. sardina throughout seasons. In Lake Xiloa, cichlid fry constituted the majority of the diet overall and cannibalism was more common, although this trend varied with the cichlid breeding season. Relative growth rates were significantly different, based on otolith mass regressions on standard length. Lake Apoyo G. dormitor generally behaved as a successful invading species, displaying exponential growth, year-round reproduction, and higher foraging success than the natural population of Lake Xiloa. Further research is planned to explore the G. dormitor invasion when the population becomes integrated into the community.

Animals commonly approach (i.e. 'inspect') potential predators. Glowlight tetras, Hemigrammus erythrozonus, have previously been shown to inspect the combined chemical and visual cues originating from novel predators and to modify their inspection (approach) behaviour depending upon the predator's diet. We conducted two experiments to determine whether tetras would inspect the chemical cues of injured prey or the dietary cues of a novel predator in the absence of any visual cues. Shoals of glowlight tetras were exposed to either distilled water (control) or the skin extract of swordtail (lacking ostariophysan alarm pheromones) or the skin extract of tetra (with alarm pheromones). There was no significant difference in the frequency of predator inspection behaviour towards swordtail or tetra skin extract compared to the distilled water controls. In the second experiment, we exposed shoals of tetras to either distilled water or the odour of Jack Dempsey cichlids, Cichlasoma octofasciatum, which had been food deprived, or fed a diet of swordtails or tetras. There was no significant difference in the frequency of predator inspection behaviour towards the odour of the starved cichlids and the odour of the fed cichlids in either of the two diet treatments. However, when tetras were exposed to the odour of cichlids fed tetras, they took significantly longer to initiate an inspection visit, remained further from the source of the chemical cues and inspected in smaller groups, compared with the odour of a starved cichlid or a cichlid fed swordtails. These data strongly suggest that tetras will inspect chemical cues alone, but only if the cue contains information about the predator. Copyright 2000 The Association for the Study of Animal Behaviour.

Se estudió la alimentación de siete especies de cíclidos (Archocentrus octofasciatus, A. spilurus, "Cichlasoma" robertsoni , "C." synspilum, "C." urophthalmus , Petenia splendida, Thorichthys meeki) en la laguna Caobas, sur de la península de Yucatán. Los muestreos se llevaron a cabo durante las estaciones seca y lluviosa de 1995. Los ejemplares medían menos de 41 mm LP. Se evaluó la frecuencia de aparición y la abundancia de las presas. Los ítemes alimentarios predominantes fueron los quironómidos, ácaros, copépodos, cladóceros y ostrácodos. La mayoría de las mojarras se mostraron zooplanctófagas, con la excepción parcial de P. splendida (piscívora), "C." synspilum y A. spilurus (herbívoras). A. octofasciatus tuvo el más amplio espectro alimentario y se consideró omnívoro. Thorichthys meeki mostró cambios cuantitativos en la dieta por hora del día, talla del pez y estación del año, no así por sexo.Feeding habits of seven cichlid species (Archocentrus octofasciatus, A. spilurus, "Cichlasoma" robertsoni, "C." synspilum, "C." urophthalmus, Petenia splendida, Thorichthys meeki) in Lake Caobas, southern Yucatan Peninsula, were studied. Samples were taken with enclosure and cast nets during the dry and rainy seasons of 1995 (day and night). The environment was characterized by measuring temperature, conductivity and pH. All individuals were below 41 mm SL (N=281). Frequency of occurrence and prey abundance were analyzed. Main prey items were chironomids, mites, copepods, cladocerans, and ostracods. The cichlids fed mainly on zooplankton, with the partial exceptions of P. splendida (piscivore), "C." synspilum and A. spilurus (herbivores). A cluster analysis showed that the most similar trophic spectra were those of T. meeki, "C." robertsoni and "C." salvini, which were also the least diverse. "C." synspilum and A. spilurus had an intermediate distance between their diets and those of other species. The species with the most distinctive feeding composition were P. splendida (with the most diverse and equitable diet) and the omnivore A. octofasciatus (whose diet was the richest one). T. meeki showed quantitative diel, ontogenetic, and seasonal diet changes, but none between sexes. "C." robertsoni, "C." salvini and "C." synspilum differ in food habits in Caobas and in other localities, a fact that underscores the trophic adaptability of cichlids. Trophic overlap between cichlids in Caobas could imply absence of competition, perhaps because resources are abundant in the ecosystem.

The function of the fin digging behaviour in increasing food availability for the offspring was analysed in the convict cichlid, Cichlasoma (Archocentrus) nigrofasciatum. Consistent individual differences in the frequency of fin digging were found in the parental fish. Examination of the gastrointestinal tract of young revealed that higher frequency of parental fin digging was associated with higher consumption of large and more profitable prey (Diptera larvae), which inhabited deep horizons of the bottom substrate and possibly were difficult to access without parental assistance. Thus, parental fin digging was initially associated with a significant increase of the offspring growth rate. However, at later brood intervals, when parental care ceased, the young of the high-digging parents were characterised by a poorer consumption of small larvae that were most accessible for them without parental aid and represented an increasingly more important component of their ration than large larvae. Offspring of the low-digging parents, on the other hand, presumably as a result of their individual experience, showed a considerably better consumption of small larvae, increasing their growth rate. As a consequence, prior parental fin digging did not affect the offspring body size after independence. Thus, there exist pronounced individual differences and alternative parental styles in the convict cichlid.

Sire, J.-Y. and Arnulf, I. 2000. Structure and development of the ctenial spines on the scales of a teleost fish, the cichlid Cichlasoma nigrofasciatum. — Acta Zoologica (Stockholm) 81: 139–158 Numerous teleost species possess ctenoid scales characterized by the presence of ctenial spines arranged in rows (the cteni) along their posterior, free margin. Whilst the morphology and function of the ctenial spines are similar to those of odontodes (extra-oral teeth), e.g. in armored catfish, their homology is questionable. To address this problem, we have studied ctenial spine development, structure, attachment to a bony support, and replacement with the aim of comparing these features to those described for odontodes. The ctenial spines have been studied in a growth series of the cichlid Cichlasoma nigrofasciatum, using light, scanning and transmission electron microscopy. Ctenial spines are entirely constituted of a collagen matrix. They lack a pulp cavity and, although their distal end can be in contact with the epidermal basal layer cells, they are not covered by an enameloid-like tissue. They are attached to the scale by means of a narrow strand of unmineralized collagen matrix acting as a ligament and allowing spines to be movable. The ctenial spines develop as prolongations of the external layer of the scale, a woven-fibroid collagen matrix, and subsequently grow by addition of parallel-fibred collagen matrix. New ctenial spines are added at the posterior scale border in waves that follow the same rhythm as the deposition of circuli in the anterior region. From the focus region to the scale border, the ctenial spines constitute lines in which only the most posterior ctenial spine is functional. The other spines that are no longer functional are not shed but resorbed from the top, and their attachment region mineralizes and thickens by deposition of new material. The remnants of spines constitute the main part of the superficial layer of the scale in which anchoring bundles attach; this region is covered afterwards by the limiting layer, a tissue devoid of collagen fibrils. Because of their tooth-like morphology (shape and size), their posterior orientation and their attachment to the scale surface, the ctenial spines resemble odontodes. Moreover, both elements perform a similar hydrodynamic function. Nevertheless, the structure and development of the ctenial spines differ completely from those of odontodes and consequently, they cannot be considered homologous elements. Ctenial spines and odontodes in teleosts provide us with a beautiful example of homoplasy; they share shape and function, but have a different origin as evidenced by their different structure and process of development.

The Lacanja River, a tropical rain forest river in southern Mexico, remains relatively undegraded and serves as a good reference for comparison with other rivers in the region that are experiencing human impacts. We sampled 12 sites from the headwaters to the mouth of the river (120 km) in both the wet and dry seasons to quantify longitudinal and seasonal patterns in fish community diversity and composition. We collected 44 species (41 native) from the river, with Cichlidae the most speciose family. The most widespread and abundant species were Brycon guatemalensis, Astyanax sp. (both Characidae), and Cichlasoma intermedium (Cichlidae). Based on fish species composition, the river could be divided into an upper, middle, and lower zone; waterfalls impeded fish movements within and between these zones. The upper zone had the lowest species diversity, and the lower zone had the highest. All of the upper zone fishes also occurred in the lower zone, and community composition changed from upstream to d...

Male convict cichlids Cichlasoma nigrofasciatum presented three females simultaneously were found to prefer larger females, even if a female's size exceeded their own. This indicates that some mechanism other than male choice, such as female choice or intrasexual competition, must contribute to male-larger assortative pairing in convict cichlids. Despite a preference for larger females, males continued to consort with smaller females when available, and a females attractiveness was a function of her size relative to other females.

Glowlight tetras, Hemigrammus erythrozonus, show a conspicuous visual display ('fin flicking') upon detecting a conspecific chemical alarm signal (alarm pheromone). We conducted laboratory studies to test two, nonmutually exclusive hypotheses regarding the function of this behaviour. To test the hypothesis that fin flicking acts as a visual alarm signal to conspecifics, we paired shoals of tetras with a stimulus tetra in an adjacent tank (separated by a one-way mirror) and exposed the stimulus tetras to conspecific skin extract (with alarm pheromone) or swordtail skin extract (which lacks ostariophysan alarm pheromone). Stimulus tetras significantly increased their frequency of fin flicking when exposed to conspecific skin extract, but not to the swordtail skin extract control. The test shoals showed a significant increase in antipredator behaviour in response to fin-flicking stimulus tetras, but not to stimulus tetras that did not fin-flick. To test the hypothesis that fin flicking serves as a predator deterrent, we paired predatory Jack Dempsey cichlids, Cichlasoma octofaciatum, with tetras in adjacent tanks and exposed the tetras to either conspecific or swordtail skin extract. Predators remained further away from the stimulus tetra, took longer to initiate a bite and displayed fewer bites towards tetras that fin-flicked compared with tetras that did not fin-flick. These results support our hypothesis that fin flicking in tetras serves as both a visual alarm signal to conspecifics and a deterring signal to predators, and suggest that individual tetras may reduce their risk of predation by fin flicking upon detecting a predation threat. Copyright 1999 The Association for the Study of Animal Behaviour.

We examined whether individual differences in patterns of parental care relate to individual differences in situations involving novelty, risk and aggression in the convict cichlid, Cichlasoma (Archocentrus) nigrofasciatum. Individual differences in situations of novelty and risk could be summarized along two axes: Freezing versus Activity and Activity-Inspection versus Freezing. However, these factors were not independent and formed a single higher-order dimension of general activity. Parental locomotor activity was negatively correlated with the Freezing versus Activity factor in females. Males that did little brood provisioning tended to be less active in the presence of a novel fish. Individuals that spent more time near their offspring at late brood stages were less inhibited in behavioural tests. Furthermore, extreme assortative mating by body size was found (r(S)=0.91). The cichlids also spawned assortatively by the factor Freezing versus Activity and by the general activity factor (r(S)/=0.49), but not by the factor Activity- Inspection versus Freezing or by aggressiveness. Copyright 1999 The Association for the Study of Animal Behaviour.

Se presentan los resultados del análisis de 474 excretas de nutria, colectadas en el río Los Pescados, Veracruz, entre diciembre de 1994 y agosto de 1995. Los grupos de presas que presentaron los más altos porcentajes de aparición fueron los peces (54.1%) y los crustáceos (30.8%); en menor grado estuvieron representados los insectos (7.5%), los reptiles (6.2%) y las aves (1.4%). Las especies con el mayor porcentaje de aparición fueron los langostinos Macrobrachium spp (21.3%) y los peces Agonostomus monticola (15.2%), Cichlasoma meeki (11.8%) y Sicydium gymnogaster (11.0%). Se detectó variación estacional en la dieta de la nutria, considerando las épocas seca y de lluvias.

Abstract Models of optimal territory size are usually tested only by demonstrating that territory size is inversely related to food abundance or intruder number. The most fundamental predictions of the models, however, have rarely been tested: i.e. the fitness of the defender is a function of territory size and the optimal territory is one of intermediate size. We tested these predictions by measuring the growth rate of large convict cichlids (Archocentrus nigrofasciatus, formerly Cichlasoma nigrofasciatum) while defending food patches against smaller intruders over a 10-day period. Food patches differed in area by more than two orders of magnitude. We manipulated food abundance so that it increased with patch size in a decelerating way. As assumed, the realized benefits of defence (weight of food eaten by the defender) and the costs of defence (chase rate and chase radius) both increased in a decelerating way with increasing patch area. As predicted, the growth rate of the defender first increased and then decreased with increasing patch size. The initial increase in defender growth rate with increasing patch size was related to an increase in food eaten, but the decrease in growth rate for fish defending the largest patches was related to the costs of defence. Fish defending large patches had a low growth efficiency, apparently because of the social stress caused by intruders in their territories. Taken together, these results support the assumptions and predictions of optimal territory size models.

Abstract We staged eight types of contests using adult male convict cichlids (Cichlasoma nigrofasciatum) to study the effects of dear enemy recognition on the defensive decisions of territorial residents when confronted by two opponents. Our observations supported the hypothesis that residents faced with two intruders simultaneously would divide the overall response shown to a single intruder between the two intruders with respect to their relative threats (i.e. sizes). Consequently, in comparison to a single-intruder circumstance, the residents' attacks against any given intruder were reduced. The relative threat of competitors was dramatically altered when one of the residents' opponents was a dear enemy neighbour. When faced with a dear enemy neighbour and an unfamiliar intruder simultaneously, residents preferentially confronted the unfamiliar opponent. That is, the establishment of dear enemy recognition between a resident and a neighbour allowed the resident to direct his aggression to the greater competitive threat, i.e. the intruder. In this case, the amount of aggression residents exhibited toward the intruder was similar to the amount of aggression against a single nonterritorial intruder. Therefore, having a dear enemy neighbour freed a resident to defend its territory against an intruder with similar efficiency compared to when the intruder had been the resident's only opponent.