Closing the reproductive cycle: Growth of the seahorse Hippocampus reidi (Teleostei, Syngnathidae) from birth to adulthood under experimental conditions

Abstract

The seahorse Hippocampus reidi is one of two seahorse species occurring in Brazil, and is in demand for the ornamental aquarium and curio trades. Juvenile H. reidi siblings ( n = 615) born in captivity were raised on a diet of wild zooplankton, enriched Artemia and wild mysid from birth to 109 days. Growth averaged 0.77 ± 0.01 mm day − 1 for the whole period. However, after the onset of sexual maturation at about 60 days of age, growth decreased to 0.31 ± 0.10 and 0.53 ± 0.09 mm day − 1 in males and females respectively. The first births of F3 juveniles were observed after 81 days of growth. All individuals were adult at the end of the study and sex ratio was 1M:1.2F. Total mortality was 11.7%, with mortality peaks apparently caused by changes in the offered diet; gradual dietary shifts may reduce the occurrence of such mortality peaks. This study indicates that H. reidi may be raised in captivity from birth to adulthood with relatively fast growth rate, low mortality and early maturity, thus, increasing the potential application of this seahorse species to commercial aquaculture and conservation initiatives.