Pairs of Holacanthus ciliaris are kept in 1,000 (n=3) or 2,000 L (n=2) tanks, in a water recirculation system (26.7 ± 1.3 ºC; 34±1‰; O₂ 6,56 mg L⁻¹; NH₃ e NO₂⁻ <0.25 ppm; 12h light). Six burrows are provided per tank. The fish receive a varied diet of seafood, sponges, Porphyra sp. and/or commercial feed, 4 times/day. Social behavior and spawning occurrence verification have been carried out since September/2023, according to fish size (Total Length - TL): 2023: 1-2 checks/month (Males: 18 ± 1 cm; Females: 6 ± 1 cm); 2024: 1-5 checks/ month (Males: 20 ± 2 cm; Females: 12 ± 1 cm; 2025: 4-12 checks/month (Males: 22 ± 2 cm; Females: 20 ± 2 cm). Eggs were collected and incubated (26.5 ± 0.5ºC; 33‰; 12h light) to record the incubation time (hours post-fertilization - hpf ) and measure the eggs (n=10) and larvae (n=3) with a stereomicroscope and Dinocapture 2.0 software.
In December 2024, two spontaneous spawnings from the same pair were recorded in a 1,000L tank. The female measured 17 cm TL, indicating that female sexual maturation in captivity differs from that in the wild (22 cm TL) (FishBase , 2025). The male measured 22 cm TL, as previously described for mature wild males (Nottingham et al ., 2003).
Unlike the other pairs in LAPOM, this pair did not exhibit agonistic behavior and occupied the same nocturnal shelter (Fig. 1).
Spawning occurred at 7:00 p.m., at the end of the light period. Egg diameter was 0.65 ± 0.02 cm, with a single oil drop measuring 0.16 ± 0.00 cm. At approximately 17 hpf the embryo had 13 somites (Fig. 2). Hatching occurred at 18 hpf . Larvae with 24 Hours after hatching contain 2.24 ± 0.01mm (TL), 2.16 ± 0.02 mm (Standard length), 0.28 ± 0.01 mm (yolk length), 0.15 ± 0.02 mm (oil drop diameter), 0.15 ± 0.01 mm (mouth width) and 0.17 ± 0.01 mm (eyes diameter).
This study highlights the potential of H. ciliaris in aquaculture, as the conditions employed favored spawning. The observed non-agonistic social behavior may indicate the effective formation of reproductive pairs. This study also shows that females with 17 cm of TL may already be sexually mature.
The absence of new spawnings highlights the need to study further aspects that may interfere in captive reproduction of these fish, such as seasonal environmental variations (e.g., natural water quality), dietary, spatial needs, among others. Future research could evaluate strategies to increase the frequency and viability of spawning, contributing to the advancement and consolidation of reproductive protocols for this highly valuable ornamental species.