We thank Universidad Jorge Tadeo Lozano (Utadeo), National Natural Parks, and the Corales de Profundidad Natural National Park (CPNNP) for their funding and support. The results are products of UTADEO’s projects Ecología y biología del pez león en dos ambientes contrastantes del Caribe colombiano. Fase V (código 822-15-17) and Invasiones biológicas en ambientes tropicales marinos: el caso del pez león (código 901-17-18), and they are within the framework of the subprogram Handling of invading species in the CPNNP. We would like to thank Deibis Seguro from Scuba Cartagena and the Diving Division and Rescue of the National Navy for their support in the capture field trips. Observations with ROV and drifting cameras were made within the projects PRY-BEM-012-14 and Mapeo de la distribución del ensamblaje de Madracis spp., which were funded by Invemar, ANH, and National Parks. We would like to thank Gabriel Navas Suárez and Adriana Bermúdez Tobón for their support in the laboratories of Universidad de Cartagena. Christian Sánchez Díaz prepared the cartography. We would also like to thank the undergraduate and graduate students that cooperated with sample processing, especially Nireth Sierra Sabalza, Shirly Bello Escobar, María Castellanos Jiménez, Margui Almario García, María Rodríguez, and Zuleima Vides Pedrozo. ASM received funding from Minciencias

Lionfish was studied in the mesophotic environment. 237 specimens were observed, most in the upper mesophotic zone. Males were larger than females and differences between sexes in growth models were found. Sixteen prey items were identified, the most important being the teleost families Acanthuridae and Monacanthidae, and the crustacean Penaeidae. The mean of δ13C was -17.08 ± 0.36 and δ15N was 8.68 ± 0.46 , with no differences between sexes. Lionfish occupies a less extensive isotopic niche in mesophotic environment than in shallow sectors; there is an isotopic niche overlap between sexes. Likewise, lionfish has specialized trophic habits. All specimens were mature and in females regression phase predominated. In females, condition factor (CF), gonadosomatic index (GSI) and hepatosomatic index (HSI) increased with gonadal development, reaching peak in the active spawning phase, and decreasing in regression. Males had a condition factor similar to spawning females, but IGS and IHS were lower.

[ES] En el ambiente mesofótico se observaron 237 especímenes de Pterois, mayoritariamente en la zona mesofótica superior. Los machos fueron más grandes que las hembras con modelos de crecimiento diferenciados. Se identificaron 16 ítems de presas, siendo los peces Acanthuridae y Monacanthidae y los camarones Penaeidae las más importantes. La media de δ13C fue -17,08 ± 0,36 ‰ y la de δ15N fue 8,68 ± 0,46 ‰, no detectándose diferencias entre sexos. La especie ocupa un nicho isotópico menos extenso que en sectores someros, tiene traslapo entre sexos y hábitos tróficos especialistas (Levin = 0,22). En hembras el factor de condición (FC), el índice gonadosomático (IGS) y el índice hepatosomático (IHS) aumentaron con el desarrollo gonadal alcanzando pico en fase de desove activo, y disminuyendo en regresión. Los machos tuvieron un FC similar al de hembras en desove, pero el IGS y el IHS fueron menores.