Growth, Condition, and Daily Ring Validation of a Cichlid in Puerto Rico

We validated otolith daily rings of Cichlasoma managuense using immersion in alizarin complexone to provide a known-age reference mark. Cichlids were stocked at 38 fish/cage into 3 121-liter cages with 5-mm mesh size within an experimental pond in Puerto Rico. The smallest 78% immediately escaped the cages and were at large in the ponds. Initial total length of cage cichlids averaged 26.5 mm compared to 20.4 mm for cichlids at large in the pond, although pond cichlids quickly overcame this deficit and realized growth rates 2 times faster than confined cichlids (1.42 mm/day vs. 0.69 mm/day). By the final sample at day 60, pond cichlids were 47% longer and 234% heavier than caged cichlids, with significantly higher values of condition. There were no differences in ring formation between the 2 groups, and rings were found to be accurate estimators of daily age. Slight under-ageing by the day 60 sample corresponded to true fish ages averaging 110 days, suggesting that the maximum accuracy would be obtained for cichlids < 100 days old. We concluded that temperate strategies of daily ageing using otoliths could be applied to this tropical cichlid species up to 100 days old.

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