Limbaugh’s damselfish (Chromis limbaughi) and the blue-spotted jawfish (Opistognathus rosenblatti) are aquarium fishes endemic to the Gulf of California, Mexico. In spite of being in the list of ornamental fishes with special protection status in the Mexican legislation for wildlife conservation (NOM-059-SEMARNAT-2001), they are among the five most heavily exploited fish species in this area. Such trade is based solely on the capture of wild specimens and the actual data on fish catches are unknown. Thus, there has long been strong suspicion of overexploitation, and possibly, species endangerment. Fortunately, greater awareness is currently raising worldwide among fish hobbyists about the environmental benefits of purchasing captive-bred and not wild fish. This presents a fantastic opportunity to lessen, and eventually eliminate, the current threat of fishing pressure on these species, since captive breeding may supply fish for the aquarium marine fish trade, and perhaps more importantly, for stock enhancement, which may be a key factor to their conservation. This study describes an ongoing investigation aiming at reproducing C. limbaughi and O. rosenblatti in captivity.
After obtaining fish collection permits (Permit No. SGPA/DGVS/00542/22 for C. limbaughi and SPARN/DGVS/04832/22 for O. rosenblatti) from the Mexican Agency for the Environment and Natural Resources (SEMARNAT), specimens of both species were captured in November 2023 in the waters adjacent to San Esteban Island in the Gulf of California, and placed, each species separately, in a recirculating aquaculture system -composed of glass aquaria, each with a capacity of 360 L- of the Kino Bay Experiment Station, University of Sonora (UNISON).
Fishes satisfactorily adapted to captivity, accepting foods in less than 48 hours after being captured. Foods offered include commercial flakes (Brine shrimp Plus Flakes, Ocean Nutrition), extruded feed (Gemma Diamond 1.5 mm, Skretting), pelleted feed made at the Aquaculture Nutrition Laboratory of UNISON (with fishmeal and krill meal as main sources of protein), as well as enriched (SELCO® Spresso INVE) on-grown, live Artemia sp., and fresh-frozen shrimp. The advances made so far are as follows. For O. rosenblatti, several spawns, in the form of egg masses, have been obtained, varying in size from 463 to 1,391 eggs. The eggs are circular in shape, with one oil drop, and a mean diameter size of 1,100 µm. Unlike other jawfishes, O. rosenblatti is not a mouth brooder and deposits the egg mass on the substrate inside a shelter. Unfortunately, none of the spawns contained fertilized eggs. For C. limbaughi, reproduction was achieved for the first time in captivity, with one pair of breeders producing four consecutive fertile spawns at intervals of approximately 18 days. Eggs are ovoidal in shape, measuring 862 ± 71.31 µm (length) × 619 ± 37.84 µm (width), with an oil globule of 200 ± 9.43 µm (diameter). Larvae were fed enriched rotifers (Brachionus plicatilis); however, they did not survive beyond day 6 of culture. Efforts are being made to further advance the captive breeding of both species.