The global marine aquarium trade relies on wild fisheries for 98% of ornamental reef species for display. Overexploitation and harmful collection techniques targeting ornamental species threaten fish populations and reef ecosystems. Aquaculture can reduce the demand for wild supplies while increasing our limited knowledge on the early life history of aquarium species. Standard protocols for egg collection, identification and larval rearing in public aquaria can facilitate research and development towards large scale aquaculture by providing an untapped source of fishes from frequent voluntary spawning events.
The aim of this study was to identify pelagic eggs and larvae collected from the mixed species Living Coral Reef exhibit at the Texas State Aquarium. Each sample was photographed and measured under a stereomicroscope to document unique characteristics for each species. Sample identities were confirmed with DNA barcoding. Mitochondrial DNA was then extracted using Chelex methodology. The mitochondrial cytochrome oxidase 1 (CO1) gene region was amplified by polymerase chain reaction (PCR) and purified with MagBind beads before sequencing. Sample sequences were compared to DNA of adult tissue and genetic information in the GenBank database.
Smallmouth (Haemulon chrysargyreum) and cottonwick (Haemulon melanurum) grunts had egg diameters of 860 ± 45 µm (n = 20) and 972 ± 30 µm (n = 11), respectively, and were genetically identified. Bicolor damselfish (Stegastes partitus) larvae, 1 day post hatch, were recognized by characteristic brain, stomach, and ventral pigmentation. Morphological characteristics, such as average egg diameter and pigmentation pattern, were distinct for each species.
Utilizing photos, measurements, and DNA sequences of adult fishes, eggs, and larvae in a public aquarium setting will allow for rapid sorting of eggs, aiding in assessing egg viability and implementing species-specific larviculture techniques of target aquaculture species. This study discusses new applications in ornamental larval culture by strengthening current research, calling for further support of sustainable fisheries and commercial aquaculture, and presenting opportunities for outreach to the public sector.