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We present evidence suggesting that some male convict cichlids (Amatitlania siquia) in Lake Xiloa, Nicaragua engage in alternative reproductive tactics (ARTs). These putative ART males were smaller than typical parental males, displayed coloration similar to breeding females, and possessed enlarged gonads. Gonadosomatic indices in these males were 16-fold higher than parental males and three-fold higher than females. This phenotype is consistent with the ‘sneaker’ or ‘satellite’ phenotype reported in other species. A survey of 282 fish in 2014 found three males (1% of all fish, 2% of males) with these characteristics. This finding is significant because convict cichlids are frequently studied in laboratory and field in the context of monogamy and biparental care.

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

The neotropical convict cichlid fish (Amatitlania siquia) is an important model species for the study of animal behaviour. It is therefore surprising that no genetic markers are available for this species. Here, we have optimised four poly- morphic microsatellite loci for use with this fish, where each locus comprises between 9 and 28 alleles. We demonstrate how these markers can be used to genotype fry (young) and for the analyses of genetic structure and prevalence of interfamilial mixing within biparental broods of wild convict cichlids. These microsatellites will facilitate future research, hitherto not possible, on the molecular, behavioural and evolutionary ecology of the convict cichlid and possibly other closely related species.

Parental investment theory states that parents should contribute more to older offspring. Differences between the sexes also influence how each parent contributes to offspring in biparental species. Here, we examined a naturally occurring population of biparental convict cichlids in Costa Rica to determine how each parent cared for offspring during two distinct offspring development stages. Consistent with the predictions of the reproductive value hypothesis, we hypothesized that the levels of parental contribution would be relative to the value that each parent places on a brood. We predicted that female parents would contribute more than male parents because female convict cichlids have lower future reproductive success than males. Additionally, we predicted that both parents should contribute more to older offspring, either due to the young’s increased susceptibility to predation (i.e., the vulnerability hypothesis) or because of the longer period of time parents have been interacting with older offspring (i.e., feedback hypotheses). This increase in investment by males should coincide with a change in the coordination of care between parents. Detailed observations of parental pairs in their natural habitat supported these predictions. Females contributed more to broods than males and were relatively unaffected by offspring age while males spent significantly more time with older, free-swimming fry. Additionally, males tended to leave younger offspring more than females did, and were more likely to do so consecutively with younger offspring. This suggests that the coordination of duties between parents changes as parental investment changes. Overall, these data support both the reproductive value and the vulnerability hypotheses, but not necessarily the feedback hypothesis.

Cichlids are unusual among fishes because they have prolonged care of their young. Convict cichlids,Cichlasoma nigrofasciatum, are monogamous and have biparental care of their young. This species has been studied extensively in the laboratory, however, little is known of their reproductive habits in nature. Four populations of convict cichlids were studied in Costa Rican streams during the long dry season in 1990 and 1991. Basic physical and chemical parameters of the study sites are described. In the study area breeding fish paired size assortatively; large males with large females and small males with small females. A comparison of the size distribution of breeding fish to that of non-breeding fish showed that small males and in some cases, small females were excluded from breeding. This suggests competition among males for nest sites and mates or female-female competition. Further evidence of intrasexual competition in females is provided by the black colour phase adopted by some females. Some of these females were active in courtship and had mature ova. Cave guarding behaviour and reuse of caves show that a ready-made spawning site is an important resource shaping the mating system of this species. This description of basic natural history can serve as a source of testable hypotheses for future research and allow the results from laboratory studies on this and related species to be interpreted within the ecological context of the natural habitat.