Age structure and growth of peacock cichlids from rivers and reservoirs of Venezuela
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Cichla temensis collected in Venezuela attained a mean standard length of 440 mm, and C. orinocensis and C. intermedia mean lengths of 309 and 321 mm, respectively. There was little evidence of size differences between sexes. Opaque zones on otoliths corresponded to the period of peak of reproductive activity and low fish body condition (K). When aggregated across sites, linear estimates for growth of fish > age I were 57.5, 27.6, and 19.6 mm year-1 for C. temensis, C. orinocensis, and C. intermedia, respectively. Fish from the Cinaruco River appeared to spawn at age I, and prior to first maturation had grown 25, 21, and 23 mm month-1, respectively, for C. temensis, C. orinocensis, and C. intermedia. There was little intersite variation in growth rates, and differences in sizes of conspecifics from different sizes were due to age differences. Cichla in captivity spawn several times per year. The present results indicate that the annual cycle or tropical wet/dry seasonality promotes reproductive seasonality in Cichla. The energetic cost of reproduction and brood defence probably constrains most individuals to one spawn per year. Conversely, populations living in relatively aseasonal reservoir environments may have several spawns per year, in which case growth zones on hard structures are difficult to interpret.