Early biological data on newly arrived invasive fish species can make a real difference in how we manage their spread. Researchers already use tools like gene analysis, but one technique is still surprisingly under-utilised: analysing the chemical makeup of calcium carbonate hard parts like scales or otoliths.
This analysis helps scientists pinpoint where fish were born and trace their movements.
When a male, non-native, yellowbar angelfish (Pomacanthus maculosus) was spotted in Brazilian waters, scientists set to work to determine where he came from.
They analysed the calcium carbonate composition of the otoliths, used DNA barcoding and determined the gut contents to explore ecological implications.
An individual of the same species was recorded during a SCUBA diving survey at the same site 420 days prior to the capture, potentially corresponding to the same individual.
This fish is not the first to invade Brazil. In 2018 a single yellowbar angelfish was filmed during a scuba diving survey on a rocky reef in the south.
Evidence points to Indian Ocean or Red Sea
By integrating the occurrence record, social context and otolith chemistry, the researchers concluded that the introduction most likely resulted from aquarium trade release. Genetic evidence suggested potential origins from the Indian Ocean or the Red Sea.
Although several studies suggest aquarium release as a possible introduction route, none have explicitly assessed this pathway using empirical tools. The researchers findings highlight the value of otolith chemistry as a forensic tool for discovering from the fish were introduced and, eventually, helping to mitigate fish invasions.
Sources
Adelir-Alves et al. (2026). Tracing yellowbar angelfish invasion pathways in the SW Atlantic using otolith chemistry. Marine Biology Research, 1–13. https://doi.org/10.1080/17451000.2026.2714812
Soeth M et al. First record of Pomacanthus maculosus (Perciformes, Pomacanthidae) in the south-western Atlantic Ocean. J Fish Biol. 2018; 93: 988–991. https://doi.org/10.1111/jfb.13791
Image credits:
- Yellowbar Angelfish: DepositPhotos
